A semiconductor package in an aspect of the present invention includes a metal board, a first frame, a second frame, and a bond. The metal board has an upper surface including a mount on which a semiconductor device is mountable. The first frame has a side surface facing a side surface of the metal board and has a smaller thermal expansion coefficient than the metal board. The second frame is on upper surfaces of the metal board and the first frame and surrounds the mount, and has a smaller thermal expansion coefficient than the metal board. The bond is between the metal board and the first frame, between the metal board and the second frame, and between the first frame and the second frame. The semiconductor package includes an alloy layer between the metal board and the bond.