A printed wiring board including a wiring substrate provided with at least one conductor circuit, a solder resist layer provided on the surface of the wiring substrate, at least one conductor pad formed from a part of the conductor circuit exposed from an opening provided in the solder resist layer, and at least one solder bump for mounting electronic parts on the conductor pad. In the printed wiring board, since the at least one conductor pad is aligned at a pitch of about 200 μm or less, and a ratio (W/D) of a diameter W of the solder bump to an opening diameter D of the opening formed in the solder resist layer is about 1.05 to about 1.7, connection reliability and insulation reliability can be easily improved.