A housing for an in-vehicle electronic control unit is disclosed. The housing includes: a case made of resin and formed into a box shape having an opening; a board received in the case and provided with an electronic part, the electronic part being mounted to the board; a cover made of metal and covering the opening of the case so that the board is arranged between the case and the cover; and multiple stays each provided to fix the cover or the case to a vehicle. The multiple stays include a first stay made of the resin and formed on the case, and a second stay made of the metal and formed on the cover.