A heat dissipating wiring board comprises: 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, wherein the circuit pattern is formed of a through groove provided in the metal wiring plate, and this through groove is made up of: 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 a dust or the like in a space of the through groove.