A line-of-sight detection device capable of achieving further improvement in line-of-sight detection accuracy, achieving low latency, and achieving low power consumption is provided. A line-of-sight detection device includes an imaging element, an illumination unit that illuminates an eyeball with a plurality of beams of illumination light, an optical element that guides respective beams of reflected light in a plurality of directions from the eyeball caused by the plurality of beams of illumination light to a direction of the imaging element, an optical system that causes the imaging element to non-selectively receive the beams of reflected light in the plurality of directions from the eyeball, and a calculation unit that converts, on the basis of the beams of reflected light in the plurality of directions from the eyeball received by the imaging element, the beams of reflected light into information of eyeball movement and/or positional information of a pupil.