There is provided an engine starting device, including: a motor generator coupled to a crankshaft of an engine; and a starter including a pinion provided in a detachable manner from a ring gear provided on the crankshaft, and configured to mesh with the ring gear when the engine is started, wherein the engine is cranked through simultaneous cranking by both of the motor generator and the starter when a condition set in advance is satisfied, and wherein, in the simultaneous cranking, the starter starts rotating after the motor generator starts rotating.