Sergei Martynov (Belarusian: Сяргей Анатолевіч Мартынаў; new transliteration Siarhei Martynau, Łacinka Siarhiej Anatolevič Martynaŭ) (born 18 May 1968) is a Belarusian 50 m rifle shooter.

Martynov was born in Vereya, Naro-Fominsky District, Moscow Oblast, Russian SFSR.

He won bronze medals in the 50 m rifle prone events at the 2000 Summer Olympics in Sydney and 2004 Summer Olympics in Athens.

Martynov won gold at the 2006 ISSF World Shooting Championships.

He has reached the maximum score of 600 points six times in competition, more than any other shooter.