A collision detection apparatus includes: an impact force detector configured to detect an impact force generated on a vehicle; a collision detector configured to detect collision with an obstacle outside of the vehicle at the time the impact force detector detects the impact force exceeding a threshold value; a collision predictor configured to predict that a bicycle being operated by a bicycle rider will collide with the vehicle before the collision with the obstacle outside of the vehicle is detected by the collision detector; and a colliding direction predictor configured to predict that the collision of the bicycle with the vehicle predicted collision with a front surface or a rear surface of the bicycle.