To enough stably hold and drive a nail shot from an injection port to the angular corner part of the base of a tongue of a floor material.

In this nailing machine for constructing the floor, the tip of a contact nose 4 provided on the tip of a tool body 2 including an impact mechanism to reciprocate in the nailing direction and constituting a safety device of the impact mechanism is pressed to the angular corner part 22 of the base of a tongue 21 of a floor material 20, and a nail is driven from the tip of the injection part 5 formed in the interior of the contact nose 4. The tip face 17 of the contact nose 4 is formed at an angle of 90 degrees or less, and the injection port 6 is opened in the apex 19 of the tip face 17.