A belt-type one-way clutch is arranged so that a case is assembled with a flat pulley so as to rotate around the central axis of the flat pulley, and that a flat belt is looped between a working surface of a rocking member supported for rocking motion by a shaft member held at both ends in shaft bores of the case and a working surface of the flat pulley, and that the rocking plate biased from a leaf spring presses one span of the flat belt to place an initial tension on the flat belt. Both the ends of the shaft member are held in the shaft bores of the case via respective bushes to suppress stress. Accordingly, larger torque can be transmitted despite use of aluminum alloy as material of the case.