A valve timing control system for an internal combustion engine, comprising a required advance amount calculating section for calculating a required advance amount on the basis of operating condition of the engine, a valve timing control section for calculating a valve timing control variable on the basis of an obtained advance amount and the required advance amount calculated by the required advance amount calculating section, and a time period measuring section for measuring an elapsed time after the start of the engine. The required advance amount calculating section makes a calculation so that the required advance amount assumes a value smaller than that in an normal state until the time period measuring section measures a predetermined period of time. Hence, exhaust gas clarification immediately after the engine start, fuel consumption and drivability can be improved.