A positioning pin 31 is inserted in a pin insertion hole 30 penetrating through a rotor 3 in an axial direction, and has both end portions held by a housing 1 and a cover 12 to prevent falling out thereof. A protrusion 31a of the positioning pin 31 protruding toward an inner side of a camshaft fitting recess 3g is engaged with a pin engagement groove 110 recessed on an outer circumference surface of an intake side camshaft 100, whereby the rotor 3 and the intake side camshaft 100 are positioned in a rotation direction.