Wiring board and semiconductor device using the same

A wiring board includes: a flexible insulating base; a plurality of conductive wirings arranged on the insulating base, end portions of the conductive wirings defining inner leads at a region where a semiconductor chip is to be mounted; and bump electrodes that are provided respectively at the inner leads of the conductive wirings. The wiring board further includes: dummy inner leads having a shape and a pitch corresponding to a shape and a pitch of the inner leads and aligned with the inner leads, the dummy inner leads being provided with dummy bump electrodes corresponding to the bump electrodes; a trunk conductive wiring provided for a group of one or an adjacent plurality of the dummy inner leads; and a branch wiring branching off from the trunk conductive wiring, the branch wiring being connected with the dummy inner leads belonging to the group corresponding to the trunk conductive wiring. Stress concentration on the inner leads during packaging of the semiconductor chip, resulting from the sparse arrangement of the electrode pads of the semiconductor chip, can be alleviated, thus suppressing a break in the inner leads.