A semiconductor device includes a semiconductor chip 5 having a first surface 5a on which a first pole 5a1 of a semiconductor element is arranged and a second surface 5b on which a second pole 5b1 is arranged and which is opposed to the first surface 5a, a first conductive member 6a connected to the first surface 5a, a second conductive member 6b connected to the second surface 5b, a first external electrode 2a connected to the first conductive member 6a and having a contact area larger than the member 6a, a second external electrode 2b connected to the second conductive member 6b and having a contact area larger than the conductive member 6b and a sealing member 3 sealing up the semiconductor chip 6 and the conductive members 6 between the first external electrode 2a and the second external electrode 2b. The sealing member 3 is provided as a result of heating a sealing material for melting and subsequent hardening. A manufacturing method of the semiconductor device is also provided to improve its electrical characteristics and productivity.