A driving tool including a driver configured to drive out a fastener, a piston to which the driver is connected, a cylinder in which the piston is disposed so as to be reciprocated, a head valve which is slidably mounted to an outer circumferential side of the cylinder and controls a flow of compressed air into the cylinder, and a seal portion which is provided to face an opening edge of the head valve. The seal portion includes a lip portion protruding along an outer circumferential surface of the head valve.