The light source device includes a first solid-state light source array emitting a first color light, a second solid-state light source array emitting a second color light, a third solid-state light source array emitting a third color light, and a light combiner for combining the first to third color lights respectively from the first to third solid-state light source arrays into a combined color light, and emitting a light flux of the combined color light in the same direction. The third solid-state light source array requiring the lowest target cooling temperature among the first to third solid-state light source arrays is disposed on a first side, and the first and second solid-state light source arrays are disposed on a second side, with an optical axis of the light flux emitted from the light combiner, as a boundary.