A bracket for attaching an electronic control unit to a panel member is provided with: a plate-shaped insertion portion to be inserted into a gap between an outer peripheral side surface of a case of an electronic control unit and an elastic pressing portion which protrudes from the outer peripheral side surface and bends and extends in an outer circumferential direction of the case; a detachment preventing latch portion to be latched with the elastic pressing portion of the case, thereby retaining the case in a detachment prevented state, when the insertion portion is inserted to a predetermined assembled position in the gap; and abutting wall portions which extend from the side surface opposed portion on both outer sides in the outer circumferential direction of the insertion portion, to come into contact with the outer peripheral side surface, in the detachment prevented state.