A magazine (103) includes a nail guide surface (106) and a movable guide wall (109). The nail guide surface (106) is linear and continuous to a nail introducing opening (105) and has a shoulder (107) for supporting the nail heads of a connected nail assembly (104). The movable guide wall (109) is confronted with the nail guide surface (106). In the magazine (103), a plurality of connected nail assemblies (104) are loaded and placed in side-by-side relation, while being in contact with each other, between the nail guide surface (106) and the movable guide wall (109). The plurality of connected nail assemblies (104) are pressed against the guide surface (106) of the magazine (103) by means of a pressing members (111) provided on the movable guide wall (109). The movable guide wall (109) is turned, for opening and closing, between a position being confronted with the nail guide surface (106) of the magazine (103) and a position at which the nail guide surface (106) is opened.