To provide a semiconductor module and a manufacturing method of the same which can sufficiently exert radiation performance by cooling fins while keeping an excellent junction between an insulation layer and the cooling fins.

The semiconductor module manufacturing method in which a heat spreader 13, 14 and a cooling fin 18, 19 are formed separately and the heat spreader 13, 14 and the cooling fin 18, 19 are joined via an insulation film 13b, 14b formed on a surface of the heat spreader 13, 14 comprises the steps of forming the cooling fin 18, 19 by placing a flat plate part 18b, 19b on a fin part 18a, 19a to bond fin peaks of the fin part 18a, 19a with the flat plate part 18b, 19b by brazing such that fillets 51 are formed at bonded parts of the fin peaks of the fin part 18a, 19a with the flat plate part 18b, 19b, and bonding the flat plate part 18b, 19b of the cooling fin 18, 19 with the insulation film 13b, 14b by soldering.