In a metal base substrate with a low-temperature sintering ceramic layer located on a copper substrate, bonding reliability is increased between the copper substrate and the low-temperature sintering ceramic layer. A raw laminated body is prepared by stacking, on a surface of a copper substrate, a low-temperature sintering ceramic green layer including a low-temperature sintering ceramic material containing about 10 mol % to about 40 mol % of barium in terms of BaO and about 40 mol % to about 80 mol % of silicon in terms of SiO2, and this raw laminated body is subjected to firing at a temperature at which the low-temperature sintering ceramic green layer is sintered. In the thus obtained metal base substrate, a glass layer composed of Cu—Ba—Si based glass with a thickness of about 1 μm to about 5 μm is formed between the metal substrate and the low-temperature sintering ceramic layer.