The disclosed engine (100) starting device is provided with: a starter (200) for starting the engine (100); and an ECU (300). The starter (200) contains: a pinion gear (260) for engaging a ring gear (110) for cranking the engine (100); an actuator (232) configured in a manner so as to cause the pinion gear (260) to engage the ring gear (110); and a motor (220) for rotating the pinion gear (260). The actuator (232) and the motor (220) can each be controlled separately. The ECU (300) has: a rotating mode for driving the motor (220) before the actuator (232) is driven; and an engagement mode for causing the pinion gear (260) and the ring gear (110) to engage by means of the actuator (232) before the driving of the motor (220). When there has been an engine (100) start request, the ECU (300) switches the selection of rotating mode and engagement mode on the basis of the rotational velocity of the engine (100) and the rate of reduction of rotational velocity of the engine (100).