A printed wiring board includes a wiring substrate, one or more conductor circuits provided on the wiring substrate, a solder resist layer provided on a surface of the wiring substrate and having multiple openings, the openings exposing multiple parts of the conductor circuits forming multiple conductor pads for mounting electronic parts, and multiple solder bumps formed on the conductor pads, respectively. The conductor pads are aligned at a pitch of about 200 μm or less, and a ratio W/D of a diameter W of the solder bumps to an opening diameter D of the openings formed in the solder resist layer is about 1.05 to about 1.7.