To provide a longitudinal mounting semiconductor device which is miniaturized and is reduced in its mounting area.

There are provided a vertically flat body section, a plurality of overlapping sections overlapped directly or indirectly on a flat surface of the body section, a lead protruded from a bottom of the body section, a plurality of leads supported in an insulating manner on the overlapped sections and protruding from lower portions of the overlapped sections, a plurality of leads disposed over the respective overlapped sections from the inside of the both section and supported in an insulating manner on the overlapped sections, at least one semiconductor chip sealed in the body section, and connection means for electrically connecting electrodes of the semiconductor chip and internal ends of the leads in the body section. The leads extending from the body section to the overlapped section extend on the overlapped section as they are, and are communicated with the leads protruding downward of the overlapped section.