A power converter (100A, 100B), comprising: a power semiconductor unit (51, 51A, 51B) in which a first circuit element configured by a power semiconductor element is mounted on an upper surface of a metal block (1, 1A) having upper and lower surfaces; a printed wiring board unit (52, 52A, 52B) in which a second circuit element (6a, 6b, 6c, 6d, 6e, 6f, 6g) is mounted on a printed wiring board that is provided with a hole for fitting the metal block (1, 1A); and a cooling heat sink, wherein the power semiconductor unit (51, 51A, 51B) and the printed wiring board unit (52, 52A, 52B) are integrated into a power conversion circuit assembly (53, 53A, 53B) by fitting the metal block (1, 1A) to the hole, characterized by comprising a ceramic material formed directly on an upper surface of the cooling heat sink to form a heat dissipation insulating layer (2, 2A), and the power conversion circuit assembly (53, 53A, 53B) being attached to the cooling heat sink in such a manner that the lower surface of the metal block (1, 1A) abuts against the upper surface of the cooling heat sink with the heat dissipation insulating layer (2, 2A) therebetween, wherein the power semiconductor unit (51, 51A, 51B) has: a relay electrode insulating layer formed by directly depositing a ceramic material on a part of the upper surface of the metal block (1, 1A); and a relay electrode formed by depositing a metallic material on an upper surface of the relay electrode insulating layer, a bonding wire or a lead frame from the first circuit element is joined to the relay electrode, and the relay electrode and a circuit pattern portion on the upper surface side of the printed wiring board (52, 52A, 52B) are connected to each other. a power semiconductor unit (51, 51A, 51B) in which a first circuit element configured by a power semiconductor element is mounted on an upper surface of a metal block (1, 1A) having upper and lower surfaces; a printed wiring board unit (52, 52A, 52B) in which a second circuit element (6a, 6b, 6c, 6d, 6e, 6f, 6g) is mounted on a printed wiring board that is provided with a hole for fitting the metal block (1, 1A); and a cooling heat sink, wherein the power semiconductor unit (51, 51A, 51B) and the printed wiring board unit (52, 52A, 52B) are integrated into a power conversion circuit assembly (53, 53A, 53B) by fitting the metal block (1, 1A) to the hole, characterized by comprising a ceramic material formed directly on an upper surface of the cooling heat sink to form a heat dissipation insulating layer (2, 2A), and the power conversion circuit assembly (53, 53A, 53B) being attached to the cooling heat sink in such a manner that the lower surface of the metal block (1, 1A) abuts against the upper surface of the cooling heat sink with the heat dissipation insulating layer (2, 2A) therebetween, wherein the power semiconductor unit (51, 51A, 51B) has: a relay electrode insulating layer formed by directly depositing a ceramic material on a part of the upper surface of the metal block (1, 1A); and a relay electrode formed by depositing a metallic material on an upper surface of the relay electrode insulating layer, a bonding wire or a lead frame from the first circuit element is joined to the relay electrode, and the relay electrode and a circuit pattern portion on the upper surface side of the printed wiring board (52, 52A, 52B) are connected to each other. a relay electrode insulating layer formed by directly depositing a ceramic material on a part of the upper surface of the metal block (1, 1A); and a relay electrode formed by depositing a metallic material on an upper surface of the relay electrode insulating layer, a bonding wire or a lead frame from the first circuit element is joined to the relay electrode, and the relay electrode and a circuit pattern portion on the upper surface side of the printed wiring board (52, 52A, 52B) are connected to each other.