Mitsunori Okamoto (岡本 充功 Okamoto Mitsunori, born June 18, 1971) 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 Yōkaichi, Shiga and graduate of Nagoya University, he obtained his medical license in 1996 and received his Ph.D in medicine from Nagoya University. He was elected to the House of Representatives for the first time in 2003. He was defeated in the 2005 election. He ran again to the House of Representatives in 2009 in the 9th district of Aichi defeating Fmr. Prime Minister Toshiki Kaifu in a stunning upset.