A keeper for an implant comprising (a) a keeper body made of a soft-magnetic material, which comprises a recess for receiving a head of an abutment having a female thread, and a female thread extending along a center axis to have communication with the recess and having a larger nominal diameter than that of the female thread of the abutment and (b) a stepped screw member comprising a small-diameter screw portion threadably engageable with the female thread of the abutment, and a large-diameter screw portion threadably engageable with the female thread of the keeper body the keeper body being strongly fixed to the abutment by the stepped screw member, when the keeper body is rotated in a threadably engaging direction, after the female thread of the abutment threadably engages the small-diameter screw portion, and after the female thread of the keeper body threadably engages the large-diameter screw portion.
