Renho, acting President of the DP, won 503 points out of a total of 849 election points, based on votes cast by the party's Diet lawmakers and party-endorsed candidates in Thursday's election as well as votes casted earlier by local lawmakers, lay members and supporters of the party, Xinhua news agency reported.
Her two opponents, former Foreign Minister Seiji Maehara and Lower House lawmaker Yuichiro Tamaki, won 230 and 116 points respectively.
Renho, has been a Upper House lawmaker representing Tokyo since 2004 and served as minister for administrative reform during the DPJ rule between 2009 to 2012.
The Democratic Party was established in March through the merger of Ishin no To and the Democratic Party of Japan (DPJ).
The new leader, with her term running through to September 2019, will be tasked with setting a new path for the party to regain the trust of voters disillusioned by its predecessor DPJ.
