FILTER DEVICE

A filter device includes a first series arm resonator in a series arm, and a first parallel arm resonator in a parallel arm, each of the first series arm resonator and the first parallel arm resonator is defined by an acoustic wave resonator including a piezoelectric layer made of lithium niobate or lithium tantalate and at least a first electrode and a second electrode on the piezoelectric layer. The acoustic wave resonator satisfies a condition of d/p being equal to or less than about 0.5, when a thickness of the piezoelectric layer is d and a distance between centers of the first and second electrodes adjacent to each other is p. An inductor connected in series to the first series arm resonator is between the first series arm resonator and the first parallel arm resonator.