PURPOSE: To obtain a band-pass filter comprising a dielectric resonator with stable mechanical and electrical characteristic over a long period with simple constitution by pressing upper/lower walls, both side walls and both end walls of a metallic case to the surface other than the coupling face of the dielectric made of a cube constituting the resonator so as to support the dielectric.

CONSTITUTION: The upper/lower faces and both side faces of the dielectrics 21∼2n made of a cube are pressed to the upper/lower walls and each inner wall face of both the side walls of the metallic case 1 to fix each dielectric to a required position and n-set of resonators connected in cascade are formed by the dielectrics 21∼2n and the metallic case 1 and the degree of coupling among adjacent resonators is kept to a required value by selecting properly the length of air gaps 31∼3n-1 among the adjacent dielectrics. Holes 41∼4n are made at nearly the center of the dielectrics 21∼2n in parallel with the direction of electric field. Input/output coupling terminals 51∼5n are fixed by lock nuts 61∼6n while an external conductor is screwed to a screw hole provided to a lower wall (or upper wall) of the metallic case 1 corresponding to each open end of the holes 41∼4n made to the dielectrics 21∼2n.