To provide a semiconductor stack, in which a ceramic plate for electrically insulating a semiconductor element and a cooler is protected from damages.

An electrically insulating and thermal conducting ceramic plate 3 between a pressure-welding type semiconductor element 1 and a cooler 2, and a heat conductive metal spacer 7 are provided. A semiconductor element 1, the metal spacer 7, the ceramic plate 3, and the cooler 2 are sequentially stacked and held in a pressed state by the use of pressing means to form a semiconductor stack. The metal spacer 7 has each disk-shaped end with a largest diameter which is larger than the post diameter of a semiconductor element 1. The metal spacer 7 has a circular groove 13 in a central direction on a circumferential part of a curved face thereof. The diameter of the circular groove 13 is as large as the post diameter of the semiconductor element 1.