An electronic component housing apparatus comprising: a case housing a first electronic component and a second electronic component having a heat quantity greater than that of the first electronic component; a first electronic component housing chamber housing the first electronic component; a second electronic component housing chamber housing the second electronic component; a first partition plate arranged between the first electronic component housing chamber and the second electronic component housing chamber, on the first electronic component housing chamber side; and a second partition plate arranged between the first electronic component housing chamber and the second electronic component housing chamber, on the second electronic component housing chamber side; a first base plate being part of the case and being thermally connected to the first electronic component, the first electronic component being installed on the first base plate; and a second base plate being part of the case and being thermally connected to the second electronic component, the second electronic component being installed on the second base plate; wherein the first partition plate and the second partition plate are provided in such a way as to at least partially face each other, a first gap part is provided between the first partition plate and a second partition plate, the first base plate and the second base plate are provided with substantially equal thicknesses/widths in such a way as to at least partially face each other, a second gap part is provided inside the first base plate as well as between the first base plate and a second base plate, the first partition plate is mounted on the first base plate, and the second partition plate is mounted on the second base plate, and the first gap part and the second gap part communicate with each other. a case housing a first electronic component and a second electronic component having a heat quantity greater than that of the first electronic component; a first electronic component housing chamber housing the first electronic component; a second electronic component housing chamber housing the second electronic component; a first partition plate arranged between the first electronic component housing chamber and the second electronic component housing chamber, on the first electronic component housing chamber side; and a second partition plate arranged between the first electronic component housing chamber and the second electronic component housing chamber, on the second electronic component housing chamber side; a first base plate being part of the case and being thermally connected to the first electronic component, the first electronic component being installed on the first base plate; and a second base plate being part of the case and being thermally connected to the second electronic component, the second electronic component being installed on the second base plate; wherein the first partition plate and the second partition plate are provided in such a way as to at least partially face each other, a first gap part is provided between the first partition plate and a second partition plate, the first base plate and the second base plate are provided with substantially equal thicknesses/widths in such a way as to at least partially face each other, a second gap part is provided inside the first base plate as well as between the first base plate and a second base plate, the first partition plate is mounted on the first base plate, and the second partition plate is mounted on the second base plate, and the first gap part and the second gap part communicate with each other.