A longitudinally-coupled-resonator surface acoustic wave filter device has a sufficient pass-band width, in which a large attenuation in a stop band near the low-frequency side of a pass band and sharp filter characteristics, and low insertion loss in the pass band are achieved. The filter device is a five-IDT longitudinally-coupled-resonator acoustic wave filter device including a first IDT, second and third IDTs arranged on either side of the first IDT in a direction of propagation of surface waves, and fourth and fifth outermost IDTs in the direction of propagation of surface waves, wherein when the first IDT has the number of electrode fingers N1 and an electrode finger pitch P1, the second and third IDTs have the number of electrode fingers N2 and an electrode finger pitch P2, and the fourth and fifth IDTs have the number of electrode fingers N3 and an electrode finger pitch P3, a relationship of N1