a collision possibility determination device includes : a detection unit which detects at least one object which moves relatively with respect to a moving body ; and a determination unit which determines a collision possibility of the moving body with the object . the determination unit defines a first factor and a second factor which are spaces between the body and the object in a travelling direction and in a width direction of the body respectively . the determination unit determines the possibility based on the two factors when the object is within a farther area from the body , and the possibility based on only the first factor when the object is within a nearer area from the body .