1. A light source unit comprising:a light-tunnel-side circulation unit that accommodates a light tunnel that is irradiated by the output light of a solid-state light source;
a phosphor wheel-side circulation unit that accommodates a phosphor wheel that is excited by the emitted light of said light tunnel;
a first wall that is provided between said light-tunnel-side circulation unit and said phosphor-wheel-side circulation unit and that is provided with a window through which the emitted light of said light tunnel passes;
a light tunnel-side heat-receiving heat sink that is provided in said light-tunnel-side circulation unit;
a light tunnel-side circulation fan that supplies and circulates gas that has passed by way of said light-tunnel-side heat-receiving heat sink, through said light-tunnel-side circulation unit, and toward said light-tunnel-side heat-receiving heat sink;
a phosphor wheel-side heat-receiving heat sink that is provided in said phosphor-wheel-side circulation unit;
a phosphor wheel-side circulation fan that supplies and circulates gas that has passed by way of said phosphor wheel-side heat-receiving heat sink, through said phosphor-wheel-side circulation unit, and toward said phosphor wheel-side heat-receiving heat sink;
a heat-radiating heat sink that is connected to said light-tunnel-side heat-receiving heat sink and said phosphor wheel-side heat-receiving heat sink by means of a heat pipe; and
a cooling fan that cools said heat-radiating heat sink.