1. A collision risk calculation device for a vehicle, comprising: a processor configure to obtain a position, a speed, and a movement direction of an obstacle at a current time; and generate a risk map indicating a range within which the obstacle can exist one unit of time after the current time and degree of risk of collision of the vehicle with the obstacle within the range, on a basis of the position, speed, and movement direction of the obstacle at the current time, wherein the processor adjusts the range so that the range is smaller in left and right directions with respect to the movement direction of the obstacle as the speed of the obstacle in the movement direction is higher, wherein the processor generates the risk map by calculating a traveling movement prediction vector in the movement direction of the obstacle on a basis of the speed and movement direction of the obstacle, calculating a left movement prediction vector in the let direction with respect to the movement direction of the obstacle on a basis of the speed and movement direction of the obstacle, calculating a right movement prediction vector in the right direction with respect to the movement direction of the obstacle on a basis of the speed and movement direction of the obstacle, calculating a left resultant vector of the traveling movement prediction vector and the left movement prediction vector, calculating a right resultant vector of the traveling movement prediction vector and the right movement prediction vector, and determining the range so that the range includes the traveling movement prediction vector and the left and right resultant vectors, and wherein the processor calculates the left and right movement prediction vectors so that the left and right movement prediction vectors are shorter as the speed of the obstacle is higher.