An apparatus for controlling an output of an air bag device (30) such
that
the output is made relatively high when a deceleration value (GF) detected
by a floor sensor (14) disposed in a central portion of a vehicle body is
higher than a threshold which changes with a velocity (GFdt)
which is obtained as a time integral of the deceleration value (GF).
The threshold is changed from a normally selected high value to a low value when
one of two deceleration values (GSL, GSR) detected by respective
two satellite sensors (16, 18) disposed in front left and right portions
of the vehicle body has reached a threshold value which changes with the velocity (GFdt).