In an electronic control unit, a current circuit part is provided on a substrate and includes a switching element. During the control of a control target, a current having a relatively large value of a predetermined value or more flows in the current circuit part. A control circuit part is provided on the substrate and includes a control part that controls actuation of the switching element on the basis of a control signal to control the control target. A current input part is provided on the substrate so as to be located opposite to the control circuit with respect to the current circuit portion. To the current input portion, the current to be supplied to the control target via the current circuit portion is input.