A millimeter wave bands semiconductor package includes a metal base body, a circuit board, and a metal cover body. The base body has a first non-penetration hole and a second non-penetration hole. The circuit board is disposed on the base body and has an input signal line and an output signal line on a front side surface thereof. The cover body is disposed on the circuit board and has a first penetration hole and a second penetration hole. The cover body is disposed such that the first penetration hole is disposed directly above the first non-penetration hole of the base body and the second penetration hole is disposed directly above the second non-penetration hole of the base body. Further, the first penetration hole and the first non-penetration hole constitute a first waveguide, and the second penetration hole and the second non-penetration hole constitute a second waveguide.