To provide a variable cam timing phase shifter with a novel configuration.

The variable cam timing phase shifter comprises a rotor 1 connected to a cam shaft 9, a spool valve 109 having a spool 104 slidable in the rotor 1, and a re-circulation check valve 302 provided in a return passage 304. A vane 16 of the rotor 1 divides a chamber formed between a housing and the rotor into an advance chamber 17a and a retard chamber 17b. When the spool 104 is at the retard position, working fluid flows only in the return passage 304 from the advance chamber 17a through an advance exhaust passage 106. When the spool 104 is at the advance position, the re-circulation check valve 302 is disposed so that the working fluid flows only in the return passage 304 from the retard chamber 17b through the retard exhaust passage 107.