It happened at around 10 a.m. at the Cherry Market on Cherry Avenue.
Deputies say the robber pointed a gun at the store clerk demanding money and cigarettes. The man took off with some cash.
Officials say the suspect was driving either an 80s model, two-door GMC JIMMY or a Chevy Trailblazer, with a black stripe painted on the sides. He was last seen heading south on Cherry Avenue and west on Central Avenue.
If you have any information, you're asked to call the Fresno County Sheriff's Office at 559-600-3111.