To prevent an intermediate frequency amplifier from oscillating while making fhe size small and thin in a radio terminal device having a shield case.

A band-pass filter 22, a filter matching circuit 24, and an intermediate frequency amplifier are provided on the circuit board of the radio terminal device, and the circuit board is covered with a metallic shield case 12 to prevent an external radio wave from entering. An opening 12a is formed in the shield case 12 opposite the band-pass filter 22 and filter matching circuit 24 to prevent the impedance of the filter matching circuit 24 from varying due to the shield case 12. The impedance variation can be prevented even by increasing the height of the metallic shield case locally only at the positions of the band-pass filter 22 and filter matching circuit 24.