PURPOSE: To prevent direct coupling between input and output parts by constituting a device so that an aperture part of a case where a microwave integrated circuit filter is stored intercepts fundamental waves.

CONSTITUTION: A dielectric filter is enclosed with a case 11 having the aperture part, and an adjusting screw 12 is provided on the upper face 11 of the case 11. Input/output lines 10 are taken to the outside from an aperture part 10. The dielectric filter is arranged and fixed on a metallic block 13. The width of the aperture part of the case 11 is set to the same value (e) as the width of a dielectric substrate 4, and its height is set to a value (a) to have the intercepting effect of fundamental waves. However, the width of the inside of the case 11 is set to a value E longer than (e), and its height is set to such value H (a<H) that the dielectric filter is stored.