Masaji (written: 政司, 政治, 政次, 正次 or 正二) is a masculine Japanese given name. Notable people with the name include:
Haguroyama Masaji (羽黒山 政司, 1914–1969), Japanese sumo wrestler
Masaji Iguro (伊黒 正次, 1913–2000), Japanese ski jumper
Masaji Kitano (北野 政次, 1894–1986), Japanese physician, general and businessman
Masaji Kiyokawa (清川 正二, 1913–1999), Japanese swimmer and businessman
Masaji Kusakabe (born 1946), Japanese golfer
Masaji Matsuyama (松山 政司, born 1959), Japanese politician
Masaji Ogino (荻野 正二, born 1970), Japanese volleyball player
Masaji Taira (平良 正次, born 1952), Japanese karateka
Masaji Tajima (田島 政治, born 1929), Japanese long jumper
