According to one embodiment, a semiconductor power converter includes first and second electrical conductors opposed to each other, first and second semiconductor elements joined to a first joint surface of the first electrical conductor, first and second convex electrical conductors joined to the first and second semiconductor elements, a junction joined to the first and second convex electrical conductors and a second joint surface of the second electrical conductor, power terminals, signal terminals, and an envelope sealing the constituent members. The envelope includes a flat bottom surface which extends perpendicular to the semiconductor elements and in which first and second bottom surfaces of the electrical conductors are exposed.