A semiconductor device includes: a first lead having an element mounting portion; a second lead located in a same plane as the first lead, with a predetermined space left between the first lead and the second lead; a molding encapsulant made of a resin for fixing the leads; and a semiconductor element affixed to a top surface of the element mounting portion of the first lead. The molding encapsulant covers at least part of each of upper and lower surfaces of the leads. A resin injection hole mark, which is a mark of a hole through which the encapsulant has been injected, is left on the encapsulant, and part of the resin injection hole mark is located above the first lead or the second lead, and the remaining part of the resin injection hole mark is located above a space between the first lead and the second lead.