A nailer includes a head and a tube is connected to a bottom of the head. A protrusion extends from an inside of the tube and an aperture is defined through the protrusion and the tube. A magnet is engaged with the aperture and a position member is mounted to the tube and seals the aperture so that the magnet will not drop from the aperture. The protrusion ensures a nail attracted by the magnet to orient an upright direction before it is ejected.