This invention is a circuit board device having a filter element. It has a base board (4), a circuit part (2) mounted on the base board (4), a filter element (5) arranged between the circuit part (2) and the base board (4), and a semiconductor component (3) mounted on the same plate as the circuit part (2) on the base board (4). The semiconductor component (3) is mounted on a thin plate region (17) that is thinner than a thick plate region (16) having its thickness increased by mounting the circuit part (2) on the base board (4). Thus, the thickness of the whole circuit board device is reduced and the filter element (5) is covered with a sufficiently thick dielectric insulating material so as to prevent deterioration in filter characteristic.