A shoe housing receives a driving force from a crankshaft and a vane rotor
rotates with a camshaft in combination. The vane rotor is received in the
shoe housing in such a way as to freely turn. Each of the vanes of the
vane rotor partitions each of three receiving chambers into a retard
hydraulic chamber and an advance hydraulic chamber. A check valve is
disposed in an advance supply passage. The check valve allows a working
oil to flow from an oil pump through the advance supply passage to the
advance hydraulic chamber and prohibits the working oil from flowing back
from the advance hydraulic chamber through the advance supply passage to
a drain.