This man beat up a 39-year-old woman as he tried to steal her cell phone aboard a Brooklyn subway train, police said.

The victim was riding a southbound Q train when the man approached and tried to rip the phone from her hand around 3 p.m. Sept. 15.

When the woman began to resist, the brute began punching and kicking her about the head and body.

The suspect eventually fled the train empty handed and the victim got off the train at the Prospect Park station.

She was not seriously injured and refused medical attention at the scene.