An engine starting device includes an air-intake flow channel in which air sucked by an engine flows. A throttle valve is provided in the air-intake flow channel for controlling airflow. An air channel bypassing the throttle valve and communicating the air-intake flow channel between an upstream side and a downstream side of the throttle valve is also provided. The air channel includes a first channel portion and a second channel portion. A first opening-closing valve opens and closes the first channel portion of the air channel and a control device controls the first opening-closing valve. The engine starting device also includes a second opening-closing valve opening and closing the second channel portion and the first channel portion. The control device determines a starting state of the engine, controls the first opening-closing valve to open the first channel portion when the engine is not in the starting state and to close the first channel portion after the engine has started. The second opening-closing valve is adapted to be switched between a first state in which the second channel portion is opened and the first channel portion is closed and a second state in which the first channel portion is opened and the second channel portion is closed.