A dummy pattern for preventing generation of air bubbles in resin sealing of a semiconductor element is provided at a corner of the semiconductor element on a tape carrier which is composed of a polyimide-based insulating tape and a copper foil pattern formed thereon. The dummy pattern makes it possible to control flow of sealing resin from the corner of the semiconductor element to a space between a lower surface of the semiconductor element and the insulating tape, resulting in prevention of air bubbles generated in resin sealing of the semiconductor element. A generation rate of air bubble can be decreased to 50% or less as compared with a conventional COF semiconductor device.