In an electronic unit accommodated in a containing device so as to be adjacent to another electronic unit accommodated in the containing device, the electronic unit includes: a housing that is formed into a tub shape, that is provided with a plate comprising an air blowing hole, and that is closed by said another electronic unit when the electronic unit and the other electronic unit are accommodated in the containing device; and an interrupting portion that interrupts power supply to the electronic unit when said another electronic unit is detached from the containing device and the housing of the electronic unit is opened.