A semiconductor device includes a semiconductor chip, a wiring formed on the semiconductor chip, a passivation film coating the wiring and having an opening for partially exposing the wiring from the passivation film an interposing film formed on a portion of the wiring and facing the opening, and a post bump raisedly formed on the interposing film and with a peripheral edge portion thereof protruding away from the opening more than a peripheral edge of the interposing film in a direction parallel to a surface of the passivation film.