A semiconductor device includes a semiconductor chip and a plurality of leads. The leads include a first lead including a supporting portion for mounting the semiconductor chip, and a projecting portion which projects in a first direction from the supporting portion. A second lead extends in a second direction non-parallel with the first direction, and one or more third leads extends in the second direction, such that a line extending in a third direction perpendicular to the first direction passes through the second lead and the one or more third leads. The second lead includes a first portion and a second portion, the first portion having a width larger than the second portion, the first portion having one side parallel to the first direction, and the first portion located between the second portion and the first lead.