In an engine which starts using a recoil starter, ignition chance during inertia rotation is not missed. If the engine 42 is rotated by the recoil starter 41, output of a power generator which is directly connected to the engine 42 is increased, and a CPU 27 is reset at timing t0. At timing t1, if pulse P1 is input from a revolution number sensor 29 to the CPU 27, the CPU 27 outputs first ignition instructions when predetermined time T1 is elapsed (t2). At timing t3, second pulse P2 is input. At that time point, since the CPU 27 is normally operated, ignition timing is obtained from an ignition timing map 30 in accordance with the revolution number calculated by a time interval between the pulses P1 and P2, and the ignition instructions are output at timing t4 in accordance with the ignition timing. Thereafter, the ignition timing is determined using the ignition timing map 30.