An electronic control unit comprising: two or more electronic components that each generate heat when energized; connection wires that connect the two or more electronic components; and a heat sink for radiating heat of the two or more electronic components and the connection wires, wherein the two or more electronic components and the connection wires are mounted on a first substrate surface that is one of the sides of a substrate, wherein the heat sink is disposed spaced apart from a top surface, of each of the two or more electronic components and the connection wires, that is the surface opposite to the first substrate surface, wherein an intermediate member having an insulating property and a heat-conductive property is provided in a gap between the heat sink, and the two or more electronic components and connection wire abutting portions each of which is at least part of the connection wires in such a way as to abut against the heat sink, and the connection wire abutting portions or the two or more electronic components, wherein the top surface of a maximum heat generating component, which is an electronic component that generates heat most among the two or more electronic components when energized, is a plane; a portion, of the heat sink, that faces the top surface of the maximum heat generating component is part of a basic plane, which is a plane of the heat sink, characterized in that the connection wires are provided with flat-plate-shaped portions which connect the two or more electronic components, and in that in the connection wire abutting portion, there is provided a flat-plate-shaped heat-transfer protruding portion that is made of a material of a kind the same as the kind of the connection wire or a material having a heat-conductive property substantially the same as that of the connection wire and protrudes toward the heat sink from the flat-plate-shaped portions; the heat-transfer protruding portion abuts against the intermediate member. two or more electronic components that each generate heat when energized; connection wires that connect the two or more electronic components; and a heat sink for radiating heat of the two or more electronic components and the connection wires, wherein the two or more electronic components and the connection wires are mounted on a first substrate surface that is one of the sides of a substrate, wherein the heat sink is disposed spaced apart from a top surface, of each of the two or more electronic components and the connection wires, that is the surface opposite to the first substrate surface, wherein an intermediate member having an insulating property and a heat-conductive property is provided in a gap between the heat sink, and the two or more electronic components and connection wire abutting portions each of which is at least part of the connection wires in such a way as to abut against the heat sink, and the connection wire abutting portions or the two or more electronic components, wherein the top surface of a maximum heat generating component, which is an electronic component that generates heat most among the two or more electronic components when energized, is a plane; a portion, of the heat sink, that faces the top surface of the maximum heat generating component is part of a basic plane, which is a plane of the heat sink, characterized in that the connection wires are provided with flat-plate-shaped portions which connect the two or more electronic components, and in that in the connection wire abutting portion, there is provided a flat-plate-shaped heat-transfer protruding portion that is made of a material of a kind the same as the kind of the connection wire or a material having a heat-conductive property substantially the same as that of the connection wire and protrudes toward the heat sink from the flat-plate-shaped portions; the heat-transfer protruding portion abuts against the intermediate member.