A semiconductor device comprising: a semiconductor chip having a first surface (SCt) on which a first electrode pad is formed, and a second surface (SCb) opposite to the first surface (SCt); a chip mounting part having a first main surface (DPt) on which the semiconductor chip is mounted via a resin adhesive material, and a second main surface (DPb) opposite to the first main surface (DPt); a plurality of external terminals extended in a first direction, and arranged side-by-side with the chip mounting part in the first direction, and arranged side-by-side with each other in a second direction perpendicular to the first direction, in a plan view; a first conductive member electrically connecting the first electrode pad of the semiconductor chip with a first external terminal (LDs) of the plurality of external terminals; and a sealing body sealing the semiconductor chip, the first main surface (DPt) of the chip mounting part, a part of each of the plurality of external terminals and the first conductive member, wherein the chip mounting part has a first part, and a second part arranged between the first part and the first external terminal (LDs), wherein the semiconductor chip is mounted on the first main surface (DPt) of the second part, wherein a first member is fixed onto the first main surface (DPt) of the first part, wherein the resin adhesive material contains thermosetting resin, wherein the sealing body contains thermosetting resin, wherein the first member is the same material as the resin adhesive material, wherein the first member is electrically separated from the plurality of external terminals other than the chip mounting part and a second external terminal (LDd) of the plurality of external terminals which is formed integrally with the chip mounting part, and wherein, in the plan view, a length of the first part of the chip mounting part in the first direction is longer than a length of the semiconductor chip in the first direction. a semiconductor chip having a first surface (SCt) on which a first electrode pad is formed, and a second surface (SCb) opposite to the first surface (SCt); a chip mounting part having a first main surface (DPt) on which the semiconductor chip is mounted via a resin adhesive material, and a second main surface (DPb) opposite to the first main surface (DPt); a plurality of external terminals extended in a first direction, and arranged side-by-side with the chip mounting part in the first direction, and arranged side-by-side with each other in a second direction perpendicular to the first direction, in a plan view; a first conductive member electrically connecting the first electrode pad of the semiconductor chip with a first external terminal (LDs) of the plurality of external terminals; and a sealing body sealing the semiconductor chip, the first main surface (DPt) of the chip mounting part, a part of each of the plurality of external terminals and the first conductive member, wherein the chip mounting part has a first part, and a second part arranged between the first part and the first external terminal (LDs), wherein the semiconductor chip is mounted on the first main surface (DPt) of the second part, wherein a first member is fixed onto the first main surface (DPt) of the first part, wherein the resin adhesive material contains thermosetting resin, wherein the sealing body contains thermosetting resin, wherein the first member is the same material as the resin adhesive material, wherein the first member is electrically separated from the plurality of external terminals other than the chip mounting part and a second external terminal (LDd) of the plurality of external terminals which is formed integrally with the chip mounting part, and wherein, in the plan view, a length of the first part of the chip mounting part in the first direction is longer than a length of the semiconductor chip in the first direction.