Patent ID: 7261023

Claim:
A bit holder device for driving a screw, while holding the screw against detachment from a bit body and retaining a state where an end of the bit body is inserted in a groove on a head of the screw, the bit holder device comprising: a cylindrical cover member removably fitted about the bit body from the end of the bit body, the cover member having an end including a magnetic attracting portion for magnetically attracting the head of the screw, the bit body protruding from the end of the cover member, the bit body being removably held by a holder body having a shank in its rear portion, and the cover member being fitted about the holder body; and a movement permitting device provided between an inner surface of the cylindrical cover member and an outer surface of the holder body, said movement permitting device permitting an axial back and forth movement of the cover member relative to the holder body, the movement permitting device comprising: a circumferential groove formed in an outer surface of the cylindrical holder body; and an elastic annular member provided on an inner surface of the cover member to be engaged with the circumferential groove, the circumferential groove having an axial length which is greater than that of the elastic annular member.