The purpose of the present invention is to swiftly start up an engine in a range in which electrical equipment having electric power supplied thereto by a battery is not reset, even in cases when the battery is insufficiently charged and the battery is deteriorated. An engine start-up device according to the present invention starts up an engine by transmitting, to the engine, the rotary force of a direct-current motor driven by a battery. The engine start-up device is provided with: a battery-voltage acquisition unit for acquiring the battery voltage of the battery; a target-current-value calculation unit which calculates, on the basis of the battery voltage acquired by the battery-voltage acquisition unit, a target current value for a motor current to be supplied from the battery to the direct-current motor; and a motor-current control unit for controlling a switching element which is connected to the direct-current motor, and through which the motor current flows, such that the motor-current value of the motor current approaches the target current value.