A metallized substrate having, disposed in the order mentioned: a ceramics substrate; a high-melting point metal layer; a base nickel plating layer; a layered nickel-phosphorous plating layer; a diffusion-inhibiting plating layer; and a gold plating layer. The base nickel plating layer being any one of a nickel plating layer, a nickel-boron plating layer, or a nickel-cobalt plating layer. The diffusion-inhibiting plating layer being any one of a columnar nickel-phosphorous plating layer, a palladium-phosphorous plating layer, or a palladium plating layer. According to the above composition, even after heating the semiconductor chips in a mounted state, the metallized substrate can make the connection strength of wire bonding favorable.