Composite filter device

A composite filter device comprising:

• a ladder filter including at least one serial arm resonator including a first serial arm resonator and at least one parallel arm resonator including a first parallel arm resonator, the serial arm resonator and the parallel arm resonator being an acoustic wave resonator including an IDT electrode;
• and
• at least one bandpass filter including one end connected to one end of the ladder filter at a common terminal;
• wherein
• the first serial arm resonator is closest to the common terminal in the serial arm resonator of the ladder filter, and the first parallel arm resonator is closest to the common terminal in the parallel arm resonator of the ladder filter;
• and
• Expression (1), or Expression (2), or Expression (3) is satisfied, where a duty of an IDT electrode of the first serial arm resonator is Sa, a duty of an IDT electrode of the first parallel arm resonator is Pa, and a duty of an IDT electrode of each of a serial arm resonator and a parallel arm resonator that are respectively included in the serial arm resonator and the parallel arm resonator and that are resonators other than the first serial arm resonator and the first parallel arm resonator is Ta:
• Sa<Pa<Ta Expression (1)
• Ta<Sa<Pa Expression (2)
• Pa<Ta<Sa Expression (3).