The robbery, which happened at 12:45 p.m. Thursday at the Tanya Nail Salon at 5245 Chestnut Street, was caught on surveillance video.
Investigators say the suspect entered the store, pulled out a gun and said "Money, money."
Workers complied and handed over cash from the store.
The suspect the fled on foot west on Chestnut Street then north on 53rd Street.
The suspect is described as a black male in his late 20s or early 30s. He was wearing a white shirt and black pants and was armed with a small, black handgun.
Anyone with information is asked to contact Philadelphia police at 215-686-TIPS (8477) or through phillypolice.com.