A quadplexer includes a first filter and a second filter whose passband has frequencies higher than the first filter. The first filter has a ladder filter structure including series resonators disposed on a first path and parallel resonators disposed on a path connecting the first path and ground. A series resonator that is closest to a common terminal among the series resonators includes an IDT electrode that excites elastic waves, and a reflector that reflects the elastic waves excited by the IDT electrode. A distance between the IDT electrode and the reflector is greater than or equal to about 0.44λ and less than about 0.5λ where λ is a wavelength of the elastic waves that is defined by an electrode cycle of the IDT electrode.