A material for an optical circuit-electrical circuit mixedly mounting substrate comprises a light permeable resin layer, and an optical circuit forming layer that is made of a light permeable resin of which refractive index increases (or decreases) when irradiated with an activating energy beam and is disposed adjacent to the light permeable resin layer, wherein a refractive index of a portion of the optical circuit forming layer is higher (or lower) than that of the light permeable resin layer when the material for the optical circuit-electrical circuit mixedly mounting substrate is irradiated with an activating energy beam so that said portion is irradiated.