Police are on the hunt for a man they say pleasured himself in public at the 7th Avenue subway station.

Police tell News 12 the man, who was spotted by a straphanger, was masturbating for about 20 minutes - while lying on a Q train platform bench.

It happened on July 31.

News 12 is told the suspect is about 35 years old, and described as 5-foot-10 and weighing about 180 pounds.

He was last seen wearing a black T-shirt, black pants and black sneakers.

Anyone with information is asked to call Crime Stoppers at 1-800-577-TIPS.