A step-by-step reciprocating mechanism for guiding a moving member along a straight guide path in the forward direction and the reverse direction. The moving member has at least one magnetic pole for each phase of a multiphase exciting current. A plurality of magnetic pole lines of a stationary member are in equal numbers at both sides of the straight guide path, and each of the magnetic pole lines has a number of fixed magnetic poles, which are successively arranged in the same pitch so as to successively oppose the magnetic poles of the moving member when the moving member travels along the straight guide path. The magnetic poles of one of the moving member and the stationary member are successively activated by the multiphase exciting current. The magnetic poles of the moving member or the stationary member are successively displaced from adjacent one of them by a pitch corresponding to one fraction of the number of phases of the multiphase exciting current.