Park Mun-su (Korean: 박문수; Hanja: 朴文秀; October 28, 1691–1756), also known as Bak Munsu, was a Korean government official in the period of King Yeongjo in the Joseon period. He was famous for the lifetime he spent protecting the Korean people from corrupt royal officials.^[1]

Park passed the state examination in 1723 and later became a secret royal inspector (Amhaengeosa; 暗行御史, 암행어사). He is the most famous secret inspector in the history of Korea, and has become something of a legendary figure, with many legends surrounding his achievements.

Bak was the son of Park Hang-han, and a member of the Goryeong Park clan. His art name was Gieun, his courtesy name was Seongbo, and his posthumous name was Chungheon.^[2]

Two portraits of Park Mun-su have been preserved and are in good condition.

• Portrayed by Yoo Jun-sang in the 2002 MBC TV series Inspector Park Moon-soo.
• Portrayed by Lee Won-jong in the 2014 SBS TV series Secret Door.
• Portrayed by Kwon Yul in the 2019 SBS TV series Haechi.