A power semiconductor element and a support member are stacked with an intermediate structure being interposed between the power semiconductor element and the support member. The intermediate structure includes a first metal paste layer and at least one first penetrating member. The first metal paste layer contains a plurality of first metal particles. The at least one first penetrating member penetrates the first metal paste layer. At least one first vibrator attached to the at least one first penetrating member penetrating the first metal paste layer is vibrated. The first metal paste layer is heated so that the plurality of first metal particles are sintered or fused.