A semiconductor apparatus 10 includes a radiator 30 on which plural semiconductor modules 20 that include semiconductor elements 21 are mounted, the semiconductor apparatus 10 characterized by the radiator 30 including a first main surface 30B and a second main surface 30C configured to be located on the opposite side of the first main surface 30B. Semiconductor module mount-surfaces 30B1, 30B2, 30C1, 30C2 are arranged in the first main surface 30B and the second main surface 30C in a zigzag pattern in cross-sectional view; and the semiconductor modules 20 are mounted onto some or all of the semiconductor module mount-surfaces 30B1, 30B2, 30C1, 30C2.