PURPOSE: To make a magnet and a vibration system light in weight, by placing yokes so as to place a plate-like armature of a cantilever rear end part between them and placing an inverted U-type magnet so as to step over the cantilever, between the armature and the yokes.

CONSTITUTION: A cantilever 31 is fixed to an armature 33. The armature 33 forms a magnetic permeable plate crosswise. The cantilever 31 and the armature 33 are installed to a holder 35 through a damper 34 of an elastic material. On the left and right, and the upper part of a vibration system 39, horizontal and vertical signal detecting yokes 40, 41, and a yoke 42 are provided. Each yoke has a coil, respectively, and each end part is placed oppositely while keeping each projecting part of the armature 33 between them. Between the armature 33 and each end part of each yoke, an inverted U-type magnet 48 is provided so as to step over the cantilever 31. The magnet 48 is magnetized in the axial direction of the lever 31.