Masanori Nishio (?? ??, Nishio Masanori, born 3 January 1949) is a Japanese politician.
Nishio was born in Ono, Hokkaido, now part of the city of Hokuto.
After graduating Kyoto University, he became a public servant in 1973.
He was appointed deputy mayor of Hakodate by its then-mayor Hiroshi Inoue in July 2003, but resigned himself in December 2006 due to a rift with the mayor over the construction of a retirement home.
He beat Inoue in the mayoral election held on 22 April 2007, and took office on 27 April.