A heat dissipating wiring board includes a metal wiring plate with a circuit pattern formed therein, a filler containing resin layer embedded with the metal wiring plate such that a top surface of the metal wiring plate is exposed, and a heat dissipating plate arranged on an under surface of the filler containing resin layer. The circuit pattern is formed of a through groove provided in the metal wiring plate. The through groove includes a fine groove that opens at the top surface of the metal wiring plate and an expanded groove that expands from a lower end of the fine groove toward the under surface of the metal wiring plate. The heat dissipating wiring board is capable of improving reliability against electric insulation due to dust or the like in a space of the through groove.