Masamitsu Oishi

is a former Japanese politician of the Democratic Party of Japan, who served in both houses of the National Diet (national legislature). A native of Sendai, Miyagi, he graduated from Rikkyo University and attended Whitworth University in Washington, United States. After having served in the House of Representatives for five terms, he lost his seat in 1996 as a member of the New Frontier Party. He was re-elected in 2000 but lost the seat again in 2003. In 2004 he ran for the House of Councillors and was elected for the first time.