To provide a resonator filter capable of contributing to the miniaturization of an apparatus and the reduction of costs.

Parts of microstrip lines or strip lines formed by using laminated substrates are used as resonant electrodes 11a, 11b, 12a and 12b, and the resonant electrode 11a and one 11b are mounted independently in parallel with the substrate-surface direction or the substrate-laminating direction and electromagnetic-field coupled. Likewise, the resonant electrodes 12a and 12b are electromagnetic-field coupled, thus constituting resonators 11 and 12. The resonators 11 and 12 are cascade-connected by connecting the resonant electrodes 11b and 12b in a loop shape. Input/output terminals P1 to P4 are fitted at both ends of the resonant electrodes 11a and 12a not used for a cascade connection in the resonators 11 and 12. Bandpass filters are manufactured by grounding the input/output terminals P2 and P4. When the input/output terminal P2 is grounded, the bandpass filter having a balun function is manufactured. The bandpass filters are operated as balanced filters without grounding the input/output terminals and using differential signals.