Abstract: [Object] Heat generation is not caused by friction in a phase varying apparatus for use with a vehicle engine. [Solution Means] A phase varying apparatus for use with a vehicle engine varies the opening/closing timing of an intake valve or an exhaust valve. The phase varying apparatus includes a rotary drum (44A) screwed to an intermediate member (30); an electromagnetic clutch (42) including a plurality of magnets (80) that are fixedly arranged at predetermined intervals along the circumferential direction of the rotary drum and that are magnetized alternately in opposite directions and a coil wound around an iron core (60); and ferromagnetic-material-made magnetic flux induction members (82, 84) having a plurality of claws (82B, 84B) close to magnetic poles of a magnet, having a slight gap between the iron core and the magnetic flux induction member, and forming a magnetic path (85) made up of the iron core and the magnets.