Automatic stop and start control system for internal combustion engine

An automatic stop and start control system for an internal combustion engine mounted at a vehicle where a clutch (2) is arranged at a power transmission passage between a transmission (3) and an internal combustion engine (1), the automatic stop and start control system for the internal combustion engine includes a controlling portion (30) controlling the internal combustion engine to automatically stop and to automatically start. The stop condition is satisfied in a case where a speed of the vehicle or the internal combustion engine is equal to or smaller than a predetermined threshold value and an acceleration pedal (15) is not depressed. The controlling portion controls a clutch actuator (21) provided separately from a clutch pedal (13) to bring the clutch in a disconnection state in a case where a shift position of the transmission is in a driving range and the clutch is in a connection state after the internal combustion engine is automatically stopped.