The vehicle-use collision mitigation apparatus includes a function of calculating a TTC indicative of a time remaining before collision with a forward obstacle on the basis of the distance to this obstacle and the reference speed therebetween, a function of alarming a driver of the vehicle of presence of a risk of collision with the obstacle if the TTC is shorter than a predetermined first time, a function of increasing a braking force generated by a braking operation performed by the driver if the TTC is shorter than a predetermined second time not longer than the predetermined first time, and a function of automatically generating a braking force if the TTC is shorter than a predetermined third time shorter than the predetermined first time. The alarming function is configured to make an alarm for a driver of a following vehicle that the preceding vehicle may decelerate abruptly.