Abstract: A high-frequency device includes plural high-frequency circuits mounted on a printed circuit board, a partition for protects the circuits from leakage or radiation of undesired signals, and a case for accommodating the printed circuit board. The partition is formed of a frame surrounded by a bottom surface of the case, bent-up strips, contact lugs, and a lid. The frame has sides shorter than the wavelength of the undesired signal. The frame reduces limitation in an arrangement of the components on the board.