In a wiring board, insulation layers and wiring conductors are alternately laminated, and a plurality of strip-shaped wiring conductors for connecting semiconductor elements are arranged side by side on the outermost insulation layer. Each of the wiring conductors partly has a connection pad to which the electrode terminals of the semiconductor elements are connected by flip-chip bonding. In the wiring board, a solder resist layer is deposited over the outermost insulation layer and the strip-shaped wiring conductors so as to have slit-shaped openings for exposing the upper surfaces of the connection pads. The solder resist layer fills up the space between the connection pads adjacent to each other and exposed within the slit-shaped openings.