To provide a lead frame module which is excellent in heat dissipation where the miniaturization of a transformer itself is established by shortening an insulating distance for the lead frame of a transformer while maintaining high durability.

This lead frame module is configured of a lead frame 1 where a circuit pattern 3 is formed of a metallic board, a transformer 4 mounted on the lead frame 1, and an insulating resin layer 2 formed by molding insulating resin on the surface of the lead frame 1. The bobbin 4a of the transformer 4 is integrally formed on the insulating resin layer 2, the coil 4c of the transformer 4 is wound around the bobbin 4a, and the terminal 4e of the coil 4c is connected to the terminal 3a of the circuit pattern 3.