A collision determination device for determining the probability of a collision between an own vehicle and a target in the predetermined determination area surrounding the own vehicle includes an orientation detection unit for detecting the orientation of the target relative to the own vehicle, an image sensor for capturing images surrounding the own vehicle, an angle calculation unit for calculating an angle θ0 formed by the movement direction of the own vehicle and the movement direction of the target, and a collision determination unit which uses image data acquired from the image sensor to calculate the state of a lane compartment line, and determines the probability of a collision between the own vehicle and the target based on the angle θ0 and the calculation result of the lane compartment line.