1. A detecting device for detecting a fake test of Blood Alcohol Concentration (BAC) that a person different from driver of a vehicle takes on behalf of the driver using an alcohol measurement device, comprising: a testee image pick-up means for picking up a face image of a testee shot during an alcohol measurement; a driver image pick-up means for picking up a face image of the driver shot within a predetermined period of time before or after the alcohol measurement; and a checking means for checking the testee and the driver based on the face images of the testee and the driver, wherein the alcohol measurement device displays a predetermined change in an appearance thereof during the alcohol measurement, the appearance change being shot together with the face of the testee, wherein the detecting device further comprises a measurement judging means for judging whether the alcohol measurement is performed properly based on the appearance change of the alcohol measurement device appearing in the face image of the testee, and wherein the detecting device further comprises: a seat-leaving monitoring means for monitoring whether the driver leaves the driver's seat of the vehicle; and a vehicle control means for limiting driving the vehicle when it is judged that the testee and the driver do not coincide or the driver left the driver's seat of the vehicle, and releasing driving the vehicle when it is judged that the testee and the driver coincide and the measured BAC is below a certain level.