A reclining device for a vehicle seat, includes a gear plate having an outer gear on an outer-diameter portion of the gear plate and configured to engage with an inner gear on an inner-diameter portion of a flange, the gear plate having an accommodation portion in an inner-diameter portion of the gear plate, and first and second cams between a flange protrusion protruding from a center of the flange and a bearing inserted into the accommodation portion, in which outer-diameter portions of the first and second cams each include a first outer-diameter portion, and a second outer-diameter portion extending from the first outer-diameter portion, in which the first outer-diameter portion is in contact with an inner-diameter portion of the bearing, and in which the second outer-diameter portion has a gap from the inner-diameter portion of the gear plate without being in contact with the inner-diameter portion of the gear plate.