Mitsuo Mitani (三谷 光男, Mitani Mitsuo, born June 16, 1959) is a Japanese politician of the Democratic Party of Japan, a member of the House of Representatives in the Diet (national legislature). A native of Kure, Hiroshima and graduate of Osaka University, he was elected to the House of Representatives for the first time in September 2005 after unsuccessful runs in 2003 and April 2005.