A semiconductor device comprising: a first thick plate portion ; a first semiconductor element on said first thick plate portion and comprising a first spacer ; wherein the first thick plate portion is electrically connected to an electrode on a lower surface side of the first semiconductor element , and that is formed by a conductor; a second thick plate portion laterally adjacent to the first thick plate portion ; a second semiconductor element on said second thick plate portion and comprising a second spacer ; wherein said second thick plate portion is electrically connected to an electrode on a lower surface side of the second semiconductor element , and that is formed by a conductor; a third thick plate portion that is electrically connected to an electrode on an upper surface side of the first semiconductor element via said first spacer , and that is formed by a conductor; a fourth thick plate portion that is electrically connected to an electrode on an upper surface side of the second semiconductor element via said second spacer , and that is formed by a conductor; a first thin plate portion integral with the second thick plate portion and extending towards the first thick plate portion , formed by a conductor, and thinner than both the first thick plate portion and the second thick plate portion ; and a second thin plate portion integral with the third thick plate portion and extending towards the fourth thick plate portion , formed by a conductor, and thinner than both the third thick plate portion and the fourth thick plate portion , wherein the first thin plate portion and the second thin plate portion are fixed together and electrically connected in a lateral position between the position of the first thick plate portion and the second thick plate portion and in a position midway between the position of the first thick plate portion and the position of the third thick plate portion in the thickness direction of the first semiconductor element . a first thick plate portion ; a first semiconductor element on said first thick plate portion and comprising a first spacer ; wherein the first thick plate portion is electrically connected to an electrode on a lower surface side of the first semiconductor element , and that is formed by a conductor; a second thick plate portion laterally adjacent to the first thick plate portion ; a second semiconductor element on said second thick plate portion and comprising a second spacer ; wherein said second thick plate portion is electrically connected to an electrode on a lower surface side of the second semiconductor element , and that is formed by a conductor; a third thick plate portion that is electrically connected to an electrode on an upper surface side of the first semiconductor element via said first spacer , and that is formed by a conductor; a fourth thick plate portion that is electrically connected to an electrode on an upper surface side of the second semiconductor element via said second spacer , and that is formed by a conductor; a first thin plate portion integral with the second thick plate portion and extending towards the first thick plate portion , formed by a conductor, and thinner than both the first thick plate portion and the second thick plate portion ; and a second thin plate portion integral with the third thick plate portion and extending towards the fourth thick plate portion , formed by a conductor, and thinner than both the third thick plate portion and the fourth thick plate portion , wherein the first thin plate portion and the second thin plate portion are fixed together and electrically connected in a lateral position between the position of the first thick plate portion and the second thick plate portion and in a position midway between the position of the first thick plate portion and the position of the third thick plate portion in the thickness direction of the first semiconductor element . <EOS>