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 (4,4a,4b) and an irradiation opening to allow light from the light source to pass; and a blower configured to blow air to generate airflow into and out of the housing through the plurality of vents, wherein the housing is rectangular and includes 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 irradiation opening is in the first surface, the plurality of vents includes a first vent and a second vent in the second surface, the first vent is located nearer the irradiation opening than the second vent, and the second vent is located near an opposite end from the irradiation opening, and the light source is located adjacent to the irradiation opening, the heat-dissipating member faces the first vent, the drive is located between the first vent and the second vent and is located between the heat-dissipating member and the blower in the housing, and the blower faces the second vent. 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 (4,4a,4b) and an irradiation opening to allow light from the light source to pass; and a blower configured to blow air to generate airflow into and out of the housing through the plurality of vents, wherein the housing is rectangular and includes 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 irradiation opening is in the first surface, the plurality of vents includes a first vent and a second vent in the second surface, the first vent is located nearer the irradiation opening than the second vent, and the second vent is located near an opposite end from the irradiation opening, and 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 irradiation opening is in the first surface, the plurality of vents includes a first vent and a second vent in the second surface, the first vent is located nearer the irradiation opening than the second vent, and the second vent is located near an opposite end from the irradiation opening, and the light source is located adjacent to the irradiation opening, the heat-dissipating member faces the first vent, the drive is located between the first vent and the second vent and is located between the heat-dissipating member and the blower in the housing, and the blower faces the second vent.