To uniformize the light intensity distribution on an irradiated surface in a light source device including a light-emitting diode (LED) array, a light source device includes a light-emitting diode (LED) array including a circuit having a substrate, a plurality of LED chips on the substrate, and a power supply. A predetermined plane is illuminated with light from the LED array. The plurality of LED chips includes first LED chips and second LED chips different from the first LED chips placed in a same column of the circuit, and the first LED chips have a placement angle different from a placement angle of the second LED chips.