A flasher type fish finder has: a motor with a rotary shaft having play in an axial direction； a display rotating disk fixed to the rotary shaft； a first installation part； and a second installation part fixed to a member not influenced by the play. In the first installation part, a magnet or a ferromagnetic material is on the rotary shaft or the display rotating disk such that the center of gravity is at the rotary shaft center. In the second installation part, a magnet or a ferromagnetic material is provided occurring an attraction force or a repulsive force in the axial direction, for the magnet or the ferromagnetic material of the first installation part. The magnet is in at least one of the first installation part and the second installation part. The surfaces of a first magnetic pole and a second magnetic pole are orthogonal to the rotary shaft.
