A collision detection apparatus comprising: 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 periphery monitoring sensor comprising a millimeter wave radar and a camera; a collision predictor configured to predict, based on target information input from the periphery monitoring sensor, 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, based on the target information input from the periphery monitoring sensor, that the collision of the bicycle with the vehicle predicted by the collision predictor is a collision with a front surface or a rear surface of the bicycle, wherein the collision detector is configured to detect the collision with the obstacle at the time the colliding direction predictor does not predict the collision with the front surface or the rear surface of the bicycle, and the impact force detector detects the impact force exceeding a first threshold value, and the collision detector is configured to detect the collision with the obstacle including the collision with the front surface or the rear surface of the bicycle at the time the colliding direction predictor predicts the collision with the front surface or the rear surface of the bicycle, and the impact force detector detects the impact force exceeding a second threshold value set to a value lower than the first threshold value. 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 periphery monitoring sensor comprising a millimeter wave radar and a camera; a collision predictor configured to predict, based on target information input from the periphery monitoring sensor, 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, based on the target information input from the periphery monitoring sensor, that the collision of the bicycle with the vehicle predicted by the collision predictor is a collision with a front surface or a rear surface of the bicycle, wherein the collision detector is configured to detect the collision with the obstacle at the time the colliding direction predictor does not predict the collision with the front surface or the rear surface of the bicycle, and the impact force detector detects the impact force exceeding a first threshold value, and the collision detector is configured to detect the collision with the obstacle including the collision with the front surface or the rear surface of the bicycle at the time the colliding direction predictor predicts the collision with the front surface or the rear surface of the bicycle, and the impact force detector detects the impact force exceeding a second threshold value set to a value lower than the first threshold value.