CASE STRUCTURE OF ELECTRONIC CONTROL UNIT

PROBLEM TO BE SOLVED: To provide an electronic control unit case structure which is capable of preventing the inside of a case housing an electronic component from rising excessively in temperature. SOLUTION: An electronic component such as a power transistor 9 or the like is housed in the case 3 of an electronic control unit 1. A breathing unit 15 is provided to the top surface of the case 3 so as to ventilate the case 3. The breathing unit 15 is composed of a filter mounting boss 17, an inner pipe 19, a breathing filter 21, and a filter protective cap 23. A breathing hole 25 is provided to the filter mounting boss 17, and the top part of the breathing hole 25 is covered with the breathing filter 21. Especially, the breathing hole 25 is provided just over the power transistor 9 so as to easily exhaust air heated by the power transistor 9.