In a semiconductor device, a lead frame is adhered to a base substrate for heat dissipation via an insulating layer, and an outward guided terminal portion is formed by perpendicularly upwardly bending an end of the lead frame after the mounting of one or more of power semiconductor elements on the lead frame. A recessed portion is formed beforehand in a portion of the lead frame to be bent, and it is ensured that the lead frame does not adhere to the surface of the base substrate in this recessed portion when the lead frame is adhered to the base substrate via the insulating layer before the bending of the lead frame. By virtue of this structure, manufacturing is simplified and manufacturing costs are reduced.