The present invention is related to a water heater for dentistry. For this water heater 10 for dentistry, a heater 12 which extends in the axial direction is provided on a water heater body section 11 which is formed into a pillar shape. First to fourth water channels 13 to 16 which spirally extend in the axial direction are formed into a plurality of layers in the outer periphery of the heater 12 in the body section 11. Adjacent ones of the plurality of layers of the water channels 13 to 16 communicate with each other on the upper ends or the lower ends, and an inlet and an outlet of water to be heated are provided on the water channels 13 to 16. The water heater 10 for dentistry is constituted in such a manner that, after water is fed from the inlet, and has passed the total length of the water channels 13 to 16, the water is fed out from the outlet as warm water. To this construct, the water heater for dentistry can suppress the volume of the device to be comparatively small, can be installed even in a comparatively narrow space, and has a favorable thermal efficiency.
