Abstract: An automatic examination system for motor vehicles can quickly and automatically examine whether an engine of an automobile or the like is good or bad without making contact with the body of the automobile or the like includes a receiver section disposed apart from the engine of the automobile or the like for receiving via a space either electrical signals or sonic signals transmitted from the engine, a period measurement section for measuring the respective periods between the respective signals received by the receiver section, a period difference calculator section for calculating the respective period differences between the respective periods measured by the period measurement section, and a good/bad decision section for deciding whether the engine is good or bad by comparing the respective period differences calculated by the period difference calculator section with a given reference value.