Masao (written: 正雄, 正夫, 正生, 正男, 正郎, 雅雄, 雅央, 雅夫, 雅勇, 雅男, 昌雄, 昌夫, 昌男, 昌朗, 昌郎, 昌大, 政雄, 政夫, 政男, 政於, 征夫, 優夫, 聖雄, 利生, 将雄, 将夫 or 眞男) is a masculine Japanese given name. Notable people with the name include:
Masao Abe (阿部 正雄, 1915–2006), Japanese philosopher and writer
Masao Adachi (足立 正生, born 1939), Japanese screenwriter and film director
Masao Akamatsu (赤松 正雄, born 1945), Japanese politician
Amatsukaze Masao (天津風 征夫, 1937–2013), Japanese sumo wrestler
Masao Arai (荒井 政雄, born 1949), Japanese sport wrestler
Masao Azuma (東 雅雄, born 1971), Japanese motorcycle racer
Baba Masao (馬場 正郎, 1892–1947), Japanese general
Masao Doi, Japanese academic
Masao Fujii (藤井 将雄, 1968–2000), Japanese baseball player
Masao Gozu (郷津 雅夫, born 1946), Japanese photographer and sculptor
Inaba Masao, Japanese military officer and rebel
Masao Haji (土師 政雄, 1925–1998), Japanese activist and academic
Masao Harada (原田 正夫, 1912–2000), Japanese triple jumper
Masao Horino (堀野 正雄, 1907–2000), Japanese photographer
Masao Inoue (井上 雅央, born 1970), Japanese professional wrestler
Masao Inoue (actor) (井上 正夫, 1881–1950), Japanese actor and film director
Masao Ito (伊藤 正男, born 1928), Japanese neuroscientist
Masao Iwasato (岩里 政男, born 1923), former President of the Republic of China (Taiwan)
Masao Kanamitsu (1943–2011), Japanese American meteorologist
Masao Kato (加藤 正夫, 1947–2004), Japanese Go player
Masao Kawai (河合 雅雄, born 1924), Japanese primatologist
Masao Kiba (木場 昌雄, born 1974), Japanese footballer
Masao Kida (木田 優夫, born 1968), Japanese baseball player
Masao Kinoshita (木下 政雄), Japanese businessman
Masao Kitagawa (北川 政夫, 1910–1995), Japanese botanist
Kiyonomori Masao (清の盛 政夫, born 1935), Japanese sumo wrestler
Masao Kobayashi (小林 正夫, born 1947), Japanese politician
Masao Koga (古賀 政男, 1904–1978), Japanese composer and guitarist
Masao Kotani (小谷 正雄, 1906–1993), Japanese theoretical physicist
Masao Kume (久米 正雄, 1891–1952), Japanese playwright, writer and poet
Masao Maeda (前田 政雄, 1904–1974), Japanese printmaker
Masao Maruyama (film producer) (丸山 正雄, born 1941), Japanese animator and film producer
Masao Maruyama (Japanese Army officer) (丸山 政男, 1889–1957), Japanese general
Masao Maruyama (scholar) (丸山 眞男, 1914–1996), Japanese political scientist and historian
Masao Mimatsu (三松 正夫, 1888–1977), Japanese volcanologist
Masao Miyamoto (宮本 政於, 1948–1999), Japanese psychiatrist
Masao Miyoshi (三好 将夫, 1928–2009), Japanese sociologist
Masao Morinaka (森中 聖雄, born 1974), Japanese baseball player
Masao Mukai (向井 正雄, born 1958), Japanese conductor
Masao Murata (村田 正夫, born 1964), Japanese judoka
Masao Nakabori (中堀 正夫), Japanese cinematographer
Masao Nakamura (中村 正雄, 1892–1939), Japanese general
Masao Nakayama (中山 利生, 1941–2011), Japanese politician and diplomat
Masao Nozawa (野澤 正雄), Japanese footballer
Masao Ohba (大場 政夫, 1949–1973), Japanese boxer
Masao Ono (大埜 正雄, 1923–2001), Japanese footballer
Masao Orihara (折原 昌夫, born 1969), Japanese professional wrestler
Masao Sasakibara (佐々木原 正夫, 1921–2005), Japanese World War II flying ace
Masao Shimizu (清水 将夫, 1908–1975), Japanese actor
Masao Suenaga (末永 正雄, born 1978), Japanese drifting driver
Masao Sugimoto (born 1967), Japanese footballer
Masao Sugiuchi (杉内 雅男, born 1920), Japanese Go player
Masao Takada, Japanese footballer
Masao Takagi (高木 正雄, 1917-1979), former President of South Korea
Masao Takahashi (born 1929), Canadian judoka
Masao Takemoto (竹本 正男, 1919–2007), Japanese artistic gymnast
Masao Takenaka (1925–2006), Japanese theologian
Masao Takiyama (滝山 正夫), Japanese television producer
Masao Tsuchida, Japanese baseball player
Masao Uchino (内野 正雄, born 1934), Japanese footballer and manager
Masao Urino (売野 雅勇, born 1951), Japanese lyricist, screenwriter and film director
Masao Watanabe (渡辺 正夫, 1888–1950), Japanese general
Masao Yamaguchi (山口 昌男, born 1931), Japanese anthropologist
Masao Yamamoto (山本 昌男, born 1957), Japanese photographer
Masao Yoshida (baseball) (吉田 正男, 1914–1996), Japanese baseball player
Masao Yoshida (nuclear engineer) (吉田 昌郎, 1955–2013), Japanese nuclear engineer
