To provide a friction pulley which can transmit a high torque.
A friction pulley (50) includes a rotatable rotary wheel (40) having a groove (4) on an outer periphery thereof, and a rubber ring (3) formed so as to be able to be accommodated in the groove (4). The friction pulley (50) is characterized by the following: the groove (4) has a pair of side surfaces (16, 26); the rubber ring (3) has a contact surface (33) which is brought into pressure contact with a rotary member so as to transmit power on an outer periphery thereof, and friction surfaces (31, 32) which are a pair of surfaces corresponding to the groove (4); at least in a power transmission state where the contact portion (33) is brought into pressure contact with the rotary member so as to transmit power, the friction surfaces (31, 32) of the rubber ring (3) are pushed to the side surfaces (16, 26) of the groove (4); and the friction pulley (50) includes separation preventing devices (51, 53) for preventing separation of the rubber ring (3) from the groove (4) in an outward direction.