A light irradiator comprising: a light source including a plurality of light-emitting elements; a heat-dissipating member thermally connected to the light source ; a drive including a drive circuit for the light source ; a housing accommodating the light source , the heat-dissipating member , and the drive , the housing having a plurality of vents and a light-emission opening to allow light from the light source to pass, the housing being rectangular and having a first surface having a first side with a first dimension and a second side with a second dimension greater than the first dimension , a second surface having the second side and a third side with a third dimension greater than the second dimension , and a third surface having the first side and the third side, the light-emission opening being in the first surface , the plurality of vents including a first vent and a second vent in the second surface , the first vent being nearer the light-emission opening than the second vent , the second vent being located opposite to the light-emission opening , the light source being adjacent to the light-emission opening , the heat-dissipating member facing the first vent , the drive being between the first vent and the second vent ; an axial fan at the second vent , the axial fan being configured to blow air from inside the housing to outside, the axial fan having a fan size greater than the first dimension and less than the second dimension ; and a plate at the second vent , the plate facing the axial fan with a spacing (D1) less than or equal to the first dimension between the plate and the axial fan . a light source including a plurality of light-emitting elements; a heat-dissipating member thermally connected to the light source ; a drive including a drive circuit for the light source ; a housing accommodating the light source , the heat-dissipating member , and the drive , the housing having a plurality of vents and a light-emission opening to allow light from the light source to pass, the housing being rectangular and having a first surface having a first side with a first dimension and a second side with a second dimension greater than the first dimension , a second surface having the second side and a third side with a third dimension greater than the second dimension , and a third surface having the first side and the third side, the light-emission opening being in the first surface , the plurality of vents including a first vent and a second vent in the second surface , the first vent being nearer the light-emission opening than the second vent , the second vent being located opposite to the light-emission opening , the light source being adjacent to the light-emission opening , the heat-dissipating member facing the first vent , the drive being between the first vent and the second vent ; an axial fan at the second vent , the axial fan being configured to blow air from inside the housing to outside, the axial fan having a fan size greater than the first dimension and less than the second dimension ; and a plate at the second vent , the plate facing the axial fan with a spacing (D1) less than or equal to the first dimension between the plate and the axial fan . <EOS>