In a high frequency filter, a multilayer structure includes a plurality of insulator layers, a first transmission line transmits an input signal, and a second transmission line is electromagnetic coupled with the first transmission line on the same insulator layer and transmits an output signal. A conductor layer defines capacitors with the first transmission line and the second transmission line with the insulator layer in between. A dielectric constant of the insulator layer that comes in contact with the first transmission line and the second transmission line is higher than a dielectric constant of an insulator layer other than the insulator layer.