The present invention provides a small, thin filter circuit showing a desired filter characteristic which is highly accurate, and producible with a high efficiency. The filter circuit includes a pair of dielectric insulating layers 2 and 3, upper and lower, each having a ground pattern 11 (16) formed on the main side thereof, and an inner wiring layer 4 formed between the dielectric insulating layers 2 and 3 and having capacitively coupled resonator conductive patterns 6 and 7 each connected at one end thereof to the ground patterns 11 and 16 via inter-layer connecting vias 12 and open-circuited at the other end. The filter circuit has formed on the inner wiring layer 4 thereof a plurality of capacitive load patterns 8 to 10 laid along the peripheries of the open-circuited end of the resonator conductive patterns 6 and 7 and electrically isolated from the ground pattern 16, and on one of the dielectric insulating layers 2 and 3 thereof correspondingly to each of the capacitive load patterns 8 to 10 a plurality of capacitive load adjusting patterns 17 to 19 electrically isolated from the ground patterns, electrically connected by the inter-layer connecting vias 24 to 26 to each other, and selectively connected to the ground pattern 16.