Provided is a durable torque limiter that can be disposed within a gear mechanism. Specifically, a torque limiter (24) has a small-diameter gear (42), a large-diameter gear (41), and a rotation-transmitting mechanism (43) for transmitting rotation between the small-diameter gear (42) and the large-diameter gear (41). The large-diameter gear (41) is provided with a cylindrical part (45) having a large-diameter toothed part (second toothed part) (41a), a plate part (46) on the inner side of the cylindrical part (45), and an annular wall part (47) protruding from the plate part (46). The small-diameter gear (42) is provided with an insertion part (54) inserted into the annular wall part (47). The rotation-transmitting mechanism (43) is provided with slits (63) that are cut into the annular wall part (47) from a second direction (X2), shafts (64) inserted into the slits (63), groove parts (66) which are formed in an outer peripheral surface (54a) of the insertion part (54) and into which the inner-peripheral portions of the shafts (64) are inserted, a coil spring (67) that exerts urging force for urging the shafts (64) toward the inner periphery when the shafts (64) protrude toward the outer periphery from the annular wall part (47), and a regulating part (68) for regulating displacement of the annular wall part (47) toward the outer periphery at the second-direction (X2) end.