Abstract: A device for fastening a holding part on an eyeglass frame placed on a plate comprises an arm adapted to receive removably the holding part and a carriage on which the arm pivots between a raised loading end position and a lowered fitting end position. The carriage is mobile on a frame in a straight line between a retracted rest end position and an advanced end of travel position. A transmission system operative between a drive system and either the arm or the carriage is such that, at least when the carriage is in the vicinity of its advanced end of travel position, the arm is in its retracted fitting position. A locking device is operative between the arm and the carriage to lock the arm releasably to the carriage when in its lowered rest position.