A viscous fluid type heater is disclosed. The heater has a rotor that is mounted on a drive shaft for integral rotation therewith in a heating chamber. The rotor rotates to shears and heats viscous fluid that is accommodated in a clearance defined between an inner surface of the heating chamber and an outer operation surface of the rotor opposed to the inner surface. The operation surface and the inner surface are formed of different materials. The inner surface and the operation surface has a coating for altering characteristics.
