A nailing machine has a contact foot coupled to the front end portion of an contact arm which is provided along a nose section adapted to hammer a nail, such that the contact arm is slidable in a nail hammering direction. The contact foot mounting structure comprises: a U-shaped mounting pin having a pair of legs, a holding piece formed at the front end of the contact arm in which the contact foot is accommodated and held, the holding piece having a pair of inserting sections, into which respective legs of the mounting pin are inserted; and a pair of engaging sections formed at the contact foot, the engaging sections being engaging with respective legs of the mounting pin.