Abstract: A vibrator for diaphragm pump and magnet holder for the vibrator wherein a stopper is formed on the inner perimeter of the side wall of the magnet insertion window in the vicinity of one main plane of the magnet holder, and that the supporting surface of the stopper for the magnet is fixed at the distance of 1/2 of the difference between the thicknesses of the magnet holder and the magnet to be inserted into the magnet insertion window, from the one main plane. A plurality of said stoppers are formed partially along the inner periphery of the magnet insertion window. Recesses are formed in appropriate portions of the perimeter of the magnet insertion window, into which the bonding agent is made to flow.