A distance image generating device includes a light emitter that emits light pulses; a light receiver that includes light receiving elements and receives reflected light; a distance calculator that generates a distance image based on an amount of the reflected light; and a light amount adjuster that determines an emission count in accordance with which the light emitter is to emit the light pulses and an exposure count in accordance with which the light receiver is to receive the reflected light based on the distance image and causes the light emitter to emit the light pulses in accordance with the determined emission count and the light receiver to receive the reflected light in accordance with the determined exposure count. The distance calculator calculates the distance based on an amount of the reflected light received at the exposure count by the light receiver.