In a semiconductor device (1), a package board (2) is provided in which a plurality of wiring layers are layered, a plurality of mounting pads (5) arranged in a matrix are provided to the uppermost wiring layer of the package board (2), and solder bumps (7) are connected to the mounting pads (5). A semiconductor chip (9) is mounted on the package board (2) via the solder bumps (7). The uppermost wiring layer of the package board (2) is formed from a resin material in which the Young's modulus is 1 GPa or lower when the temperature is 10 to 30° C., and the elongation at break is 50% or higher.