An internal combustion engine includes a hydraulically-driven variable valve timing device for adjusting the opening timing and the closing timing of an intake valve and configured to include a start retard position for decompression that is retarded further from the most retarded position during a normal operating state, and a control system configured to start a cranking operation of the internal combustion engine while the variable valve timing device is positioned in the start retard position for decompression, to determine during the cranking operation whether operating oil has drained from the variable valve timing device, when it has been determined that oil has drained from the variable valve timing device, to set a delay time between the cranking operation start and an advance operation of the variable valve timing device longer than the situation in which operating oil is replete.