PURPOSE: To measure the characteristic of an igniter with high precision, by varying a revolving speed and measuring various characteristics.

CONSTITUTION: The 1st counter 21 regards the output of a voltage-controlled type variable frequency oscillating circuit 4 as a crank angle signal B to count the number of clock pulses generated during this period. The 2nd counter 22 counts the number of clock pulses between the generation point of an ignition signal C outputted from an ignition system controlled by an igniter 9 synchronously with the generation of an ignition spark and the generation point of a signal B generated right after it. A central processor 17 causes interruption when a reference signal A and signals B and C are generated to fetch the counting end values of the counters 21 and 22 and also counts the number of the signals B in the period from the generation point of the signal A to the generation point of the signal C to calculate various characteristics of the igniter 9 from those obtained values, thereby writing the results in memories 23 and 24 successively.