A quadplexer includes a filter of a first duplexer that has a passband with frequencies lower than a filter of a second duplexer. A series resonator closest to a common terminal of the filter includes split resonators that are each an elastic wave resonator including an IDT electrode and a reflector, and include first and second split resonators with impedance characteristics having ripples different from each other in a certain frequency range higher than an anti-resonant frequency of the series resonator closest to the common terminal, that is defined by a pitch of electrode fingers included in the reflector, and that is included in a passband of the filter.