An acoustic wave filter device includes longitudinally coupled resonator-acoustic wave filters having a balanced-unbalanced conversion function, and increases the amount of attenuation in an attenuation band and improves the isolation characteristics when the acoustic wave filter device is used as a reception filter of a duplexer. The acoustic wave filter device includes an unbalanced terminal, first and second balanced terminals, first and second longitudinally coupled resonator-acoustic wave filters that are connected between the unbalanced terminal and the first balanced terminal and between the unbalanced terminal and the second balanced terminal, respectively, a first parallel resonator connected between the first balanced terminal and a ground potential, and a second parallel resonator connected between the second balanced terminal and the ground potential. The electrostatic capacitance of the first parallel resonator is different from the electrostatic capacitance of the second parallel resonator. Among the first parallel resonator and the second parallel resonator, the wavelength of the first parallel resonator having a relatively small electrostatic capacitance is shorter than the wavelength of the second parallel resonator having a relatively large electrostatic capacitance.