A torque limiter includes a cylindrical member, and a shaft member which is fitted rotatably in the cylindrical member. The cylindrical member has a main body portion having in an interior thereof an oil pressure expansion chamber for pressing an inner circumferential surface of the cylindrical member against an outer circumferential surface of the shaft member and an oil release passage which is opened to the oil pressure expansion chamber at one end portion while being closed tightly at the other end portion and which is positioned further radially outwards than an outer circumferential surface of the main body portion. When the cylindrical member stays still relative to the shaft member, the other end portion of the oil release passage is accommodated within a cap member which is screwed to be fixed in a threaded hole. When the cylindrical member rotates relative to the shaft member, the other end portion of the oil release passage is broken by the cap member, whereby the oil release passage is opened to the outside. When the cylindrical member is rotated relative to the shaft member in such a state that the cap member is not screwed in the threaded hole and in such a state that the oil release passage is not opened to the outside, the other end portion of the oil release passage moves in the circumferential direction within circumferentially extended groove while being spaced apart from the circumferentially extended groove.