A multilayer semiconductor device includes an interconnect substrate provided with first electrode lands and connection terminals on a top surface; a semiconductor chip mounted on the top surface of the interconnect substrate; first connecting members connecting the first electrode lands to a circuit formation surface of the semiconductor chip; first metal posts provided on the connection terminals; encapsulating resin filling a space between the interconnect substrate and the semiconductor chip; a package provided with second electrode lands on a main surface; and second connecting members electrically connecting the first metal posts to the second electrode lands.