A semiconductor device includes (i) a tape base material, (ii) a wiring pattern, (iii) a semiconductor element which is electrically connected with the wiring pattern, (iv) a top-side insulating protective film which covers a top surface of the tape base material and has an top-side opening section provided in a region where the top-side insulating protective film faces the semiconductor element, and (v) a reverse-side insulating protective film which covers a reverse surface of the tape base material and has a reverse-side opening section provided on a reverse side below the top-side opening section. The top-side insulating protective film has a protruding opening section extending outwardly from the region. An opening of the reverse-side opening section is 1.00 time to 8.50 times larger in an area than the region.