A semiconductor device includes a film substrate having an interconnection pattern provided on a surface thereof, a semiconductor chip mounted on the film substrate and having an electrode provided on a surface thereof, and an insulative resin portion provided between the film substrate and the semiconductor chip, the resin portion having been formed by applying an insulative resin on at least one of the film substrate and the semiconductor chip and filling a space defined between the film substrate and the semiconductor chip with the resin when the semiconductor chip is mounted on the film substrate, wherein the interconnection pattern has a projection which has a sectional shape tapered toward the electrode of the semiconductor chip and intrudes in the electrode thereby to be electrically connected to the electrode.