Seiji (written: 誠二, 誠治, 誠史, 誠司, 誠次, 清二, 清治, 清次, 清志, 聖二, 聖治, 聖司, 征二, 征治, 征爾, 正慈, 成二, 精二, 菁児, 菁滋, 静児, 政二 or せいじ in hiragana) is a masculine Japanese given name. Notable people with the name include:

• Seiji Aochi (青地 清二, 1942–2008), Japanese ski jumper
• Seiji Ara (荒 聖治, born 1974), Japanese racing driver
• Seiji Arikawa (有川 清次, 1929–2016), Japanese politician
• Seiji Chiba (千葉 誠治, born 1964), Japanese film director and producer
• Seiji Ebihara (海老原 清治, born 1949), Japanese golfer
• Seiji Fujie (藤江 精二, born 1941), Japanese basketball player
• Seiji Fukushi (福士 誠治, born 1983), Japanese actor
• Seiji Hagiwara (萩原 誠司, born 1956), Japanese politician
• Seiji Hirao (平尾 誠二, born 1963), Japanese rugby union player
• Seiji Hisamatsu (久松 静児, 1912–1990), Japanese film director
• Seiji Honda (本田 征治, born 1976), Japanese footballer
• Seiji Inagaki (born 1973), Japanese hurdler
• Seiji Kameda (亀田 誠治, born 1964), Japanese musician and record producer
• Seiji Kameyama (亀山 晴児, born 1979), Japanese rapper better known as WISE
• Seiji Kaneko (金古 聖司, born 1980), Japanese footballer
• Seiji Katagiri (片桐 清二, born 1946), Japanese aviator
• Seiji Kihara (木原 誠二, born 1970), Japanese politician
• Seiji Kimura (木村 誠二, born 2001), Japanese footballer
• Seiji Kishi (岸 誠二), Japanese anime director
• Seiji Kobayashi (小林 誠司, born 1989), Japanese professional baseball player
• Seiji Koga (古賀 誠史, born 1979), Japanese footballer
• Seiji Kubo (born 1973), Japanese footballer
• Seiji Kudo (工藤 誠二, born 1945), Japanese cross-country skier
• Seiji Kumagai (熊谷 誠二, born 1967), Japanese voice actor
• Seiji Kurata (倉田 精二, born 1945), Japanese photographer
• Seiji Maehara (前原 誠司, born 1962), Japanese politician
• Seiji Mataichi (又市 征治, born 1944), Japanese politician
• Seiji Matsunaga (松永 清志, born 1954), Japanese sport wrestler
• Seiji Matsuyama (松山 せいじ, born 1975), Japanese manga artist
• Seiji Miyaguchi (宮口 精二, 1913–1985), Japanese actor
• Seiji Mizushima (水島 精二, born 1966), Japanese anime director
• Seiji Morita (森田 清次), Japanese film editor
• Seiji Nakamura (仲村 正治, born 1931), Japanese politician
• Seiji Nemoto (根本 誠次, born 1961), Japanese sport wrestler
• Seiji Noma (1878–1938), Japanese writer and publisher
• Seiji Ogawa (小川 誠二, born 1934), Japanese biologist
• Seiji Oko (大古 誠司, born 1948), Japanese volleyball player
• Seiji Ono, Japanese table tennis player
• Seiji Osaka (逢坂 誠二, born 1959), Japanese politician
• Seiji Ozawa (小澤 征爾, born 1935), Japanese conductor
• Seiji Saito (斉藤 誠司, born 1986), Japanese footballer
• Seiji Sakaguchi (坂口 征二, born 1942), Japanese professional wrestler
• Seiji Sasaki (佐々木 誠二, born 1965), Japanese voice actor
• Seiji Shibata (柴田 征二, born 1938), Japanese fencer
• Seiji Shinkai (新海 征治, born 1944), Japanese chemist
• Seiji Suzuki (鈴木 政二, born 1948), Japanese politician
• Seiji Takahashi (高橋 聖二, born 1993), Japanese ice hockey player
• Seiji Takaiwa (高岩 成二, born 1968), Japanese actor
• Seiji Takaku, Japanese psychologist
• Seiji Takeda (竹田 菁滋, born 1960), Japanese television producer
• Seiji Tōgō (東郷 青児, 1897–1978), Japanese painter and artist
• Seiji Ueda (上田 清二, born 1952), Japanese astronomer
• Seiji Yamada (山田 誠司, born 1966), Japanese ski mountaineer
• Seiji Yamamoto (山本 征治, born 1970), Japanese chef
• Seiji Yokoyama (横山 菁児, born 1935), Japanese composer
• Seiji Yoshida (吉田 清治, 1913–2000), Japanese writer and communist

Fictional characters

• Seiji Matoba, the main antagonist of Natsume's Book of Friends
• Seiji Amasawa, one of the main characters of Whisper of the Heart
• Seiji Sagara, a supporting character in HappinessCharge PreCure!

See also

• Celadon, known in Japanese as Seiji (青磁)