PURPOSE: To prevent idle ignition occurring in the vicinity of top dead center upon completion of exhaust stroke, in an ignitor employing no distributor, by producing an ignition permitting signal with correspondence to the crank shaft rotary pulse and cam shaft rotary pulse.

CONSTITUTION: A rotor 7 is arranged on a crank shaft 12 while a rotor 2 is arranged on a cam shaft 1 rotatable with 1/2 speed of the rotation of crank shaft 12 and pulsers 8, 3 are arranged near to respective rotor 7, 2. The output signals from said pulsers 8, 3 are shaped 10, 9 and fed to an electronic lead angle control circuit 11 to produce an ignition control signal with correspondence to the rotary angle of crank shaft 12. In accordance to the output from respective sensor 8, 3 first ignition permitting signal is produced from FF26 where said outputs are fed to ignition permitting signal generating circuit 15 thus to produce second ignition permitting signal during predetermined interval from initial stage of intake process to the initial stage of combustion process. Consequently, idle ignition can be prevented reliably under exhaust stroke.