The back surface of a semiconductor wafer having a plurality of chip-forming regions each provided with a plurality of connection pads on the surface is bonded to a dicing tape, followed by fully cutting the semiconductor wafer along a cut line so as to form a cutting groove. Then, a front side protective film is formed on the front surface. The front side protective film has an open portion exposing the central portion of the connection pad, and is filled in the cutting groove. After formation of a columnar electrode connected to the connection pad via a wiring, a sealing film is formed on the front side protective film. Further, the cutting groove filled with the front side protective film is cut in substantially the center in the width direction, followed by peeling off the dicing tape so as to form individual semiconductor devices each forming a chip.