ENGINE STARTING DEVICE AND STARTING METHOD

PROBLEM TO BE SOLVED: To provide an engine starting device and a starting method by means of which it is possible to restart an engine as fastest as possible within the allowable range for decreases in battery voltage.SOLUTION: A revolution detection sensor 110 detects the rotation speed of a DC motor 105. A control means 109 performs PWM control for electrification of the DC motor. The control means 109 continuously changes the current-carrying rate D of the PWM control on the basis of the rotation speed of the DC motor detected by the rotation detection sensor 110 so that the electric current flowing to the DC motor stays at a preset constant value. Thus, the battery electric current from the start of motor electrification to the completion of engine starting is held at a constant value, the value being a nearly constant electric current value, which is within the allowable battery voltage range and near the allowable value.