a semiconductor device that enables a test for individual ic chips mounted on an interposer is provided . in the semiconductor device having the interposer on which a first ic chip and a second ic chip are mounted , the first ic chip and the second ic chip are connected to outside the interposer by input wring and output wiring , respectively , and a transistor element serving as a switch is inserted in series into the wiring connecting between the first ic chip and the second ic chip .