1. A collision risk calculation device comprising: a movement information obtaining unit that obtains a speed and a movement direction of an obstacle; and a risk map generator that generates a risk map indicating a range within which the obstacle can exist after one unit of time and degree of risk of collision of an own vehicle with the obstacle within the range, on a basis of the speed and the movement direction of the obstacle obtained by the movement information obtaining unit, wherein the risk map generator changes the range in left and right directions with respect to a traveling direction of the obstacle, on a basis of the speed of the obstacle in the traveling direction.