A man was whacked in the head with a Master Lock at a Queens subway station by a stranger wearing a “Bad Boy” jacket, police said Sunday.

Cops released a photo of the suspect Sunday and are asking the public’s help identifying him and tracking him down.

The 26-year old victim was approached by the attacker at the Queens Blvd.-Union Turnpike station in Kew Gardens about 1:55 a.m. on Oct. 11, cops said.

The assailant whipped out out the metal lock and hit the man in the head with it, causing a gash, before running off, police said. A witness flagged down a cop.

Medics took the victim to Jamaica Hospital in stable condition.

The suspect wore a multicolored jacket with the logo “Bad Boy” emblazoned across the chest. He id described as having a light complexion, light beard and thin build and was wearing glasses, black pants and black sneakers.

Anyone with information is asked to call Crime Stoppers at (800)-577-TIPS. All calls will be kept confidential.