The present invention relates to an electronic control unit for a vehicle. The electronic control unit for a vehicle can improve waterproof efficiency of a space between an upper case and a lower case in order to prevent damage to internal components, thereby improving steering stability.

A junction box assembly and an upper case is provided. The upper case includes a peripheral wall and an interior wall having an outer wall and an inner wall. The outer wall is dimensioned to define a u-shaped structure. The inner wall is dimensioned to define a closed loop. The inner wall is disposed within and spaced apart from the outer wall. The upper case further includes a rib disposed on an outer surface of an inner back wall. The rib extends longitudinally along the inner back wall and is dimensioned to contact an inner surface of a top cover of the junction box assembly so as to prevent water from entering the upper case.