An ignition timing measuring and display device of an internal combustion engine (1) having a magneto (A) includes a reference RPM signal pulse detector (2) for detecting a reference RPM signal pulse of the internal combustion engine (1) and an ignition noise pulse detector (4) for detecting ignition noise of an electromagnetic wave generated in the vicinity of an ignition plug (3) when ignition is carried out in the internal combustion engine (1) and calculates ignition timing generated by the magneto (A) based on the signal pulse and the ignition noise pulse and displays it. Since the ignition timing of the internal combustion engine can be easily monitored, maintenance can be carried out to the internal combustion engine and an ignition device to realize a necessary operating performance of the internal combustion engine.