A core (20) is housed in a box (10) in which a box upper board (11) is electrically insulative and nonmagnetic. The core has front and rear side legs (23) directed toward the box upper board (11). A coil (26) is wound around the core (20). An air way (12a) is formed in a box bottom board (12). A blower (16) is attached to the air way. Other air ways which cooperate with the air way (12a) to form air pathways passing over the coil (26) are formed in box side boards (13). Pulse current or alternating current is supplied to the coil (26) to generate magnetic fluxes toward a region from a front of the urethral orifice to a rear of the anus, so that urinary incontinence is treated by eddy currents induced in the living body.