A variable valve timing control device comprises a housing member integrally rotating with either one of a crankshaft or a camshaft of an internal combustion engine, a rotor member assembled to the housing member so as to be rotatable relative thereto, including at least one of vane portions forming an advanced angle chamber and a retarded angle chamber within the housing member, and integrally rotating with the other one of the crankshaft or the camshaft; a fluid pressure circuit for controlling operation fluid to be supplied to or discharged from the advanced angle chamber and the retarded angle chamber, an engaging groove formed at the housing member in circumferential direction and including an advanced angle side end portion and a retarded angle side end portion, a lock member provided at the housing member and being freely projecting/retreating, and a projecting portion provided at the rotor member and projecting outward, which is sandwiched between either one of the end portions of the engaging groove and the lock member being in a projecting state.