In a lead frame board, while a heat radiation wall member formed by a resin having a relatively high thermal conductivity is provided in a low heat-resistance heat generating component mounting region where a low heat-resistance heat generating component is mounted, heat block wall members formed by resins having relatively low thermal conductivities are provided in a high heat-resistance heat generating component mounting region where a high heat-resistance heat generating component is mounted and in a non-heat generating component mounting region where a non-heat generating component is mounted. Thus, heat block is performed between the low heat-resistance heat generating component mounting region and the high heat-resistance heat generating component mounting region and non-heat generating component mounting region, and a heat radiation function is enhanced in the low heat-resistance heat generating component.