Collision detecting apparatus for vehicle

The invention provides a collision detecting apparatus for a vehicle, including an integrating means (I) for cumulatively integrating an output from an acceleration sensor (S) when the output exceeds a specific calculation start level, and a collision detecting means (C) for outputting a collision signal (X) when a cumulative integral value ( SIGMA G) calculated by the integrating means exceeds a threshold value ( alpha ) wherein the collision detecting apparatus is intended to accurately perform collision decision by preventing the occurrence of erroneous detection based on a vibration waveform of acceleration of the vehicle as a result of, for example, riding past a stepped portion. The collision detecting apparatus includes a vibration waveform detecting means (W) for detecting that an output waveform from the acceleration sensor (S) is a specific periodical vibration wave form. When the vibration waveform detecting means (W) detects the vibration waveform, the integrating means does not stop the cumulative integration even if the output (G) returns to a specific calculation end level (G0) and continues the cumulative integration for the output (G) that contains not only an output component corresponding to a negative acceleration but also an output component corresponding to a positive acceleration.