A light source apparatus, comprising: a light source section including a plurality of light source units; a heat dissipation section including one or more fins commonly thermally connected to the plurality of light source units, a first mounting portion on which a suction mechanism that sucks heated air through the one or more fins is mounted, a second mounting portion on an opposite side of the first mounting portion, on which the light source section is mounted, the second mounting portion including a first intake port serving as an intake port for cooling air guided to the one or more fins, and a second and a third opposed intake ports between the first and second mounting portions, wherein the one or more fins includes a plurality of fins each having a rectangular planar plate shape with opposed, parallel first and second elongated peripheral edges, and wherein the fins of the plurality of fins are superimposed one to the other so as to have an approximate rectangular parallelepiped shape as a whole,substantially filling the space between the first and the second mounting portions such that the elongated peripheral edges are aligned, the first mounting portion is disposed on a first surface in which the first elongated peripheral edges of the plurality of fins are aligned, and the second mounting portion is disposed on a second surface opposed to the first surface, in which the second elongted peripheral edges opposed to the first elongated peripheral edges of the plurality of fins are aligned. a light source section including a plurality of light source units; a heat dissipation section including one or more fins commonly thermally connected to the plurality of light source units, a first mounting portion on which a suction mechanism that sucks heated air through the one or more fins is mounted, a second mounting portion on an opposite side of the first mounting portion, on which the light source section is mounted, the second mounting portion including a first intake port serving as an intake port for cooling air guided to the one or more fins, and a second and a third opposed intake ports between the first and second mounting portions, wherein the one or more fins includes a plurality of fins each having a rectangular planar plate shape with opposed, parallel first and second elongated peripheral edges, and wherein the fins of the plurality of fins are superimposed one to the other so as to have an approximate rectangular parallelepiped shape as a whole,substantially filling the space between the first and the second mounting portions such that the elongated peripheral edges are aligned, the first mounting portion is disposed on a first surface in which the first elongated peripheral edges of the plurality of fins are aligned, and one or more fins commonly thermally connected to the plurality of light source units, a first mounting portion on which a suction mechanism that sucks heated air through the one or more fins is mounted, a second mounting portion on an opposite side of the first mounting portion, on which the light source section is mounted, the second mounting portion including a first intake port serving as an intake port for cooling air guided to the one or more fins, and a second and a third opposed intake ports between the first and second mounting portions, wherein the second mounting portion is disposed on a second surface opposed to the first surface, in which the second elongted peripheral edges opposed to the first elongated peripheral edges of the plurality of fins are aligned.