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 (G1) 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 (G2) 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 (G1) and the second gap part (G2) 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 (G1) 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 (G2) 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 (G1) and the second gap part (G2) communicate with each other. <EOS>