A nut job is being sought by police for torching a Brooklyn gynecology office twice in one week, police said.

The suspected arsonist first targeted Boro Park Obstetrics & Gynecology shortly before 2 a.m. last Sunday, cops said.

The firebug gained entrance to the Flatbush office building by repeatedly tossing a fire hydrant cap at the front door, a stunning surveillance video reveals.

With his back facing the camera, the suspect appears to ignite an incendiary device before tossing it inside the building.

He then calmly walks away.

In a second attack at 4 a.m. Friday, the suspect used a sledge hammer to break down the door, according to police. Police are searching for the pyromaniac, who is believed to be in his 40s. A motive behind the two fires is unclear at this time.