Engine start control system

An engine start control system includes a starter (27) and a motor generator (7) capable of starting an engine (1). The engine start control system further includes a controller (26) that determines the rotational resistance of the crankshaft (3) based on cooling water temperature of the engine (1) or viscosity of the engine oil, and then selects the starting mode of the engine(1) by the starter (27) and a motor generator (7) based on the determination. Consequently, the startability of the engine (1) is improved according to the state of the vehicle.