A light irradiating device (1, 1A, 1B, 1D, 1E, 1F) which extends on an irradiating surface in a first direction and irradiates linear light having a predetermined line width in a second direction intersecting the first direction, the light irradiating device (1, 1A, 1B, 1D, 1E, 1F) comprising: a substrate which is substantially parallel to the first direction and the second direction; a plurality of light emitting diode light sources which are disposed on a surface of the substrate with predetermined intervals along the first direction and emit light in a third direction intersecting the surface of the substrate; a cooling unit which includes a heat transporting unit (212, 212A; 212B) which is at least partially in contact with a rear surface of the substrate, and which extends in an opposite direction to the third direction from the substrate, and which transports heat generated from the LED light sources in the opposite direction to the third direction, and a plurality of heat radiating fins which are mounted on the heat transporting unit (212, 212A; 212B) to radiate heat of the heat transporting unit (212, 212A; 212B) into the air; a LED driver circuit (300A, 300B) which drives the plurality of LED light sources; a housing which has one surface of the second direction and the other surface opposite to the one surface, an opening sucking and exhausting external air on the one surface, accommodates the cooling unit and the LED driver circuit (300A, 300B), and forms a wind tunnel in an area where the cooling unit and the LED driver circuit (300A, 300B) are disposed; and a fan (400A, 400B) which is provided at an opposite side to the third direction of the cooling unit to guide the external air to the wind tunnel and generate an air current in the wind tunnel, wherein the cooling unit is disposed along the one surface of the housing and the LED driver circuit (300A, 300B) is disposed along the other surface of the housing, characterized in that the plurality of heat radiating fins is disposed with a predetermined interval along the third direction. a substrate which is substantially parallel to the first direction and the second direction; a plurality of light emitting diode light sources which are disposed on a surface of the substrate with predetermined intervals along the first direction and emit light in a third direction intersecting the surface of the substrate; a cooling unit which includes a heat transporting unit (212, 212A; 212B) which is at least partially in contact with a rear surface of the substrate, and which extends in an opposite direction to the third direction from the substrate, and which transports heat generated from the LED light sources in the opposite direction to the third direction, and a plurality of heat radiating fins which are mounted on the heat transporting unit (212, 212A; 212B) to radiate heat of the heat transporting unit (212, 212A; 212B) into the air; a LED driver circuit (300A, 300B) which drives the plurality of LED light sources; a housing which has one surface of the second direction and the other surface opposite to the one surface, an opening sucking and exhausting external air on the one surface, accommodates the cooling unit and the LED driver circuit (300A, 300B), and forms a wind tunnel in an area where the cooling unit and the LED driver circuit (300A, 300B) are disposed; and a fan (400A, 400B) which is provided at an opposite side to the third direction of the cooling unit to guide the external air to the wind tunnel and generate an air current in the wind tunnel, wherein the cooling unit is disposed along the one surface of the housing and the LED driver circuit (300A, 300B) is disposed along the other surface of the housing, characterized in that the plurality of heat radiating fins is disposed with a predetermined interval along the third direction.