宇多天皇（うだてんのう、貞観9年5月5日（867年6月10日）-承平元年7月19日（931年9月3日））は、日本の第59代天皇（在位：仁和3年11月17日（887年12月5日）-寛平9年7月3日（897年8月4日））。名は定省（さだみ）。光孝天皇の第七皇子。母は桓武天皇の皇子仲野親王の娘・皇太后班子女王。一度臣籍降下し、源氏の姓を賜って源定省を称したが、後に実力者の関白藤原基経の後押しで887年（仁和3年）8月25日に皇族に復帰し、翌8月26日に皇太子に立てられる。これには宇多天皇が基経の異母妹である内侍司藤原淑子の猶子であったことが大きい。同日に光孝天皇が病没したため践祚し、11月17日に即位した。第一皇子敦仁親王（のちの醍醐天皇）は、女御（贈皇太后）藤原胤子の子。藤原胤子は内大臣藤原高藤女で、宇多天皇が若い時からの妻の一人。藤原胤子の他、女御は藤原温子、橘義子、菅原衍子、橘房子。藤原温子は基経の女で、宇多帝即位後に入内した。女御藤原胤子が病没後、皇太子敦仁親王を猶子とし、醍醐天皇即位に伴い、皇太夫人となる。晩年は東七条宮に住んだため、東七条后、七条后とも称される。橘義子からは真寂法親王があり、菅原道真女を妻としたことから、後年菅原道真の誣告に際してその名が出た。菅原衍子は菅原道真の女。皇子皇女多数。宇多天皇の孫は、ほとんどが源氏の姓を賜り、臣籍に降下した。宇多天皇から出た源氏を宇多源氏といい、藤原胤子の子・敦実親王から出た系列が最も栄えた。敦実親王の子・源雅信は左大臣を務め、その女・源倫子は藤原道長の正室となり、一条天皇中宮藤原彰子や関白藤原頼通の母となった。朝廷貴族としての地位を維持した子孫としては、公家の綾小路家などがあり、また雅信から近江に土着した佐々木氏が出ている。系図藤原時平と菅原道真を重用した（寛平の治）。888年（仁和4年）に造立された勅願寺が仁和寺。その後、醍醐天皇に譲位し、仁和寺に入って法皇と称した。天皇の譲位については古くは仏道専心説が有力であったが、近年では藤原氏からの政治的自由を確保するためとする説、一旦臣下から皇族に復帰して即位したためにこれに不満を抱く他の皇族の皇位要求の動きに先んじた説などがある（後述の『大鏡』の陽成上皇の発言はその暗示ともされる）。また『寛平御遺誡』には右大臣源能有の死による強い衝撃について書かれており、退位と結びつける見方もある。一方、陽成上皇との関係は微妙であった。『大鏡』には、陽成上皇が宇多天皇のことを、「あれはかつて私に仕えていた者ではないか」と言ったという逸話が残っているが、陽成上皇が復位を画策しているという風説は天皇を悩ませた。保延年間に書かれた『長秋記』（保延元年6月7日条）によれば、陽成上皇が宇多天皇の内裏に勝手に押し入ろうとしたために、上皇といえども天皇の許しなく内裏に入る事が禁じられたが、後に昌泰の変が起きた時に醍醐天皇に菅原道真の左遷を止めさせようとして内裏に入ろうとした宇多上皇がこの決まりを盾に阻まれたと記されている。皇位継承者不在の危機にあたり、臣籍降下した者が即位した例であるが、当時在世中の元良親王らを超越しての即位であり、藤原淑子・基経による擁立劇という側面もある。即位直後におきた「阿衡事件」は、天皇を自らの傀儡にしたい基経と、若き天皇との主導権争いでもある。事件は天皇の譲歩に終わったものの、基経が想像するよりは英明な人物であったから、菅原道真を重用するなど、次第に「親政」色を強めてゆくことに成功した。『寛平御遺誡』、『寛平御記』の著書を残す。晩年は病気がちの醍醐天皇に代わって、実際の政務を執っていたいう説もある。「延喜天暦の治」と賞せられる醍醐天皇・村上天皇の「善政」とされるものの多くは宇多天皇（法皇）の政策の延長上に過ぎず「寛平の治」と呼ぶのが妥当ではないかという説もある。譲位後に行った大掛かりな和歌の行事である「亭子院歌合」は、国風文化の盛行の流れを後押しするものである。通説では譲位後の在所の名称より宇多天皇と追号された（追号も諡号の一種とする場合もあるが、厳密には両者は異なる）と言われているが、実際の居宅は仁和寺御室・亭子院・六条院を主としていたという（宇多院は元は父の光孝天皇の親王時代の邸宅で、宇多天皇はここで成長したからだという異説もある）。また、寛平法皇、亭子院（ていじのいん）、朱雀院太上天皇などの名称でも呼ばれた。仁和寛平陵墓は京都市右京区鳴滝宇多野谷にある大内山陵（おおうちやまのみささぎ）とされる。全ての天皇は皇居の宮中三殿の一つの皇霊殿に祀られている。

emperor uda ( june 14 , 867 - september 8 , 931 ) , the fifty-ninth japanese emperor , was in power from december 9 , 887 to august 8 , 897 .the last name is sadami .emperor uda was the seventh prince of emperor koko .his mother was empress dowager hanshi-joo , who was the daughter of emperor kammu 's son , imperial prince nakano .although he once left the imperial family and was granted the surname of genji and called minamoto no sadami , he returned to the imperial family on august 29 , 887 with the help of kampaku , chief adviser to the emperor , fujiwara no mototsune , and became a prince on august 30 , 888 .this is strongly related to the fact that emperor uda was the adopted son of naishi no tsukasa fujiwara no yoshiko , who was mototsune 's half-sister .he became emperor on november 21 , the day emperor koko passed away due to ill health .the first child , imperial prince atsugimi ( later called emperor daigo ) , was the son of nyogo ( empress dowager zo ) , fujiwara no inshi ( taneko ) .fujiwara no inshi was one of the wives of emperor uda when he was young , and was a daughter of naidaijin fujiwara no takafuji .the nyogo were fujiwara no inshi , fujiwara no onshi ( yoshiko ) , tachibana no gishi ( noriko ) , sugawara no enshi ( hiroko ) and tachibana no boshi ( fusako ) .fujiwara no onshi ( yoshiko ) was mototsune 's daughter and became one of the emperor uda 's wives after his enthronement .after nyogo fujiwara no inshi died of illness , imperial prince atsugimi was adopted and she became the prince 's wife when emperor daigo was enthroned .because she lived in higashi-shichijo-no-miya during the last part of her life , she was also called higashi-shichijo-ko or shichijo-ko .shinjaku-hosshinno was the son of tachibana no gishi ( noriko ) , whose wife was the daughter of sugawara no michizane ; the name became apparent years later , when sugawara no michizane had a false charge brought against him .sugawara no enshi ( hiroko ) was a daughter of sugawara no michizane .there are many princes and princesses .most of emperor uda 's grandchildren were granted the surname genji and left the imperial family .the genji clan , which originated from the emperor uda family , is called uda-genji ; those who came from the genji group of fujiwara no inshi 's daughter , imperial prince atsumi , had the most power .minamoto no masanobu , imperial prince atsumi 's son , became sadaijin ; his daughter , minamoto no rinshi , was a wife of fujiwara no michinaga and mother of emperor ichijo chugu fujiwara no shoshi and kampaku fujiwara no yorimichi .the lords of the imperial palace who kept their positions were the ayanokoji family and the sasaki clan , who were descendents of the masanobu , who had originally moved to ohmi and were indigenized and gave themselves the name sasaki .genealogythe emperor appointed fujiwara no tokihira and sugawara no michizane to positions of trust ( kampyo-no-chi ) .the construction of the ninna-ji temple was ordered by emperor uda in 888 .the imperial throne was passed to emperor daigo , and later emperor uda became a high priest at ninna-ji temple .in the old days it was believed that emperor uda came to power due to his strict buddhist belief ; however , one recent theory says the reason was that dominant political control had been taken away from the fujiwara clan , or that it was done to stop the complaints from the royal families after emperor uda came into power by coming back to the imperial family , although he had become an allegiant ( as indicated by the retired emperor yozei in his remark in " okagami ( the great mirror ) , " which is described below ) .emperor uda mentioned in " kampyo-goyuikai " / " kampyo-no-goyuikai ( a group of precepts for governing ) " that he was greatly shocked by the death of udaijin , minamoto no yoshiari , which could have been one of the reasons he left the throne .on the other hand , the relationship with the retired emperor yozei was tense .according to an anecdotal story in " okagami ( the great mirror ) , " the retired emperor yozei said that emperor uda used to serve him . it is also said to have been a big headache for the retired emperor uda as emperor yozei had tried to restore his government .according to the " chousyu-ki " ( an article of june 7 , 1135 ) written during the hoei period , when the retired emperor yozei had tried to enter the palace , emperor uda forbade the retired emperor yozei from entering the palace without his permission ; however , later on emperor uda tried to enter the palace when the shotai-no-hen / shotai incident happened , and he tried to ask emperor daigo to stop sugawara no michizane 's degradation , but could not do so because of the regulation that he himself had made .this was an example of a member of the imperial family who abdicated and then returned and became the emperor because there was no one to succeed the enthronement ; it is said that the event of emperor uda 's enthronement could have been set up by fujiwara no yoshiko and mototsune , although imperial prince motoyoshi was still alive .a power struggle occurred after the young emperor uda was enthroned , when he and yoshitsune , who wanted control over the emperor , fought against each other in the " ako affair . "although the affair was settled by emperor 's concession , the emperor was smarter than mototsune believed he was , and he changed the government into the " shinse " style ; for example , he appointed sugawara no michizane to a position of trust .the emperor uda wrote " kampyo-goyuikai " / " kampyo-no-goyuikai ( a group of precepts for governing ) " and " kampyo-gyoki ( emperor uda 's diary ) . "it is said that the emperor uda took actual control of the government while emperor daigo remained sick in his last years .some people said that " engi-tenryaku-no-chi , " which was supposed to be governed well by emperor daigo and emperor murakami , should be called " kampyo-no-chi , " since the actual politics were based on emperor uda 's ( priest in a high position ) style .there was a big waka ( japanese poetry ) ceremony called " teiji-in uta-awase , " which was held after emperor uda came to power , thus representing the great influence of the kokufu bunka ( japan 's original national culture ) .it is said that the name of emperor uda came from the place where he abdicated ( tsuigo is sometimes considered to be a type of posthumous name , but strictly speaking these are two different names ) ; however , he spent most of the time at ninna-ji temple omuro , teijino-in and rokujo-in ( though another theory says the reason was that emperor uda spent his childhood at uda-in , which was the house of his father , emperor koko , when he was the imperial prince ) .he was also called kampyo-hoo , teijinoin and dajo-emperor suzakuin .ninnakampyothe imperial mausoleum is located at ouchiyama no misasagi , in uda-no-tani , narutaki , ukyo-ku , kyoto city .all the emperors are enshrined in koreiden , one of the kyuchu-sanden ( three shrines of the imperial court ) .