Disengageable pulley device comprising a pulley mounted on a shaft by means of a rolling bearing and of a freewheel, the pulley comprising a rim mounted on the periphery of a one-piece outer race of substantially tubular shape comprising, on an inner surface, at least one raceway for rolling elements and at least one contact seat of cylindrical revolution for lock-up elements of the freewheel, a one-piece inner race forming a torque transmission shaft and including, on an outer surface coming opposite the outer race, at least one raceway for the rolling elements and at least one contact seat of cylindrical revolution for the lock-up elements of the freewheel.