An electronic circuit unit includes an electronic circuit unit main body that is housed in a shelf, a first rotating shaft that is provided on a front side of the electronic circuit unit main body, a lever member rotatably provided about the first rotating shaft for urging the electronic-circuit-unit-main-body toward a depth side of the shelf, a second rotating shaft that is provided in the lever member and extends parallel to the first rotating shaft, a locking member rotatably provided about the second rotating shaft. When the lever member is rotated in a first direction about the first rotating shaft, the electronic circuit unit main body is moved toward a depth side of the shelf. When the lever member is rotated in a second direction, opposite to the first direction, the electronic circuit unit main body is moved toward a front side of the shelf.