The present disclosure relates to a driving tool which operates a piston by compressed air to drive out a fastener, and particularly to a technology for preventing a foreign matter from entering an O-ring groove and the like of a head valve. The driving tool is provided with a foreign matter removing member (37) with a protruding portion (37c) facing a circumferential surface of a head valve (34). Therefore, a sealed port (34b) is covered by the foreign matter removing member (37), thereby preventing the foreign matter such as ice (50) from entering the sealed part (34b). When the head valve (34) slides to move relatively with respect to the foreign matter removing member (37), the protruding portion (37c) functions in a manner of erasing the circumferential surface of the head valve (34), and the ice (50) attached on the circumferential surface of the head valve (34) can be removed by the foreign matter removing member (37).