Abstract: A method for checking the operability of a vehicular safety system which comprises an acceleration sensor for providing a pair of differential output signals, a first and second vehicle collision discriminators having a differential amplifier responsive to the pair of differential output signals, respectively, a pair of current controllers responsive to the first and second distriminators, respectively, whereby a firing current is supplied to a firing actuator through the pair of current controllers when the vehicle collision is detected. The method is characterized in that one of the differential amplifier is changed in arrangement so as to be able to respond to an in-phase input, and a test signal for making the acceleration sensor produce pair of check signals in phase is applied to the acceleration sensor. Then the operability of the safety system is checked on the basis of the potential developed at the firing actuator at that time without the activation of the actuator.