PURPOSE: To improve the group delay characteristic of the ladder type electric filter constituted by connecting the plural steps of basic unit circuits by enlarging the electrostatic capacity of a serial resonator in the rear step rather than that of a connecting resonator in the preceding step.

CONSTITUTION: The electrostatic capacity of a serial resonator S2 in the rear step is enlarged rather than that of a connecting resonator S1 in the preceding step. Namely, at a filter circuit constituted by connecting the two steps of basic unit circuits formed by L-shaped connection between serial resonators S1/S2 and parallel resonators P1/P2, for example, the electrostatic capacity of both the parallel resonators P1 and P2 is set at 780F so as to be different from that of the serial resonators S1 and S2. Thus, by differing the electrostatic capacity of the respective serial resonators S1 and S2 and enlarging the electrostatic capacity of the serial resonator S2 in the rear step rather than that of the serial resonator S1 in the preceding step, the group delay characteristic is improved and made optimum for the filter circuit such as the mobile radio equipment, etc., of a digital modulation system.