An Oldham coupling includes: a driven Oldham flange that is formed at a drive-side rotor; a drive Oldham flange that is formed at a planetary rotor; and an Oldham intermediate that is configured to synchronize rotation of the driven Oldham flange and rotation of the drive Oldham flange. A thrust section is formed at a rotor plate portion which is a portion other than the Oldham coupling. The thrust section is configured to limit tilting of the planetary rotor relative to the driven Oldham flange when the thrust section contacts the planetary rotor in an axial direction. There is satisfied a relationship of θ2>θ1 where: θ1 is a maximum tilt amount of the planetary rotor relative to the driven Oldham flange; and θ2 is a maximum tilt amount of the planetary rotor in a clearance formed at the Oldham coupling.