A duplexer included in a radio frequency module is used in a communication band in which the transmit band in a single communication band includes a first transmit band and a second transmit band overlapping each other and in which the receive band in the single communication band includes a first receive band and a second receive band overlapping each other. A transmit filter unit in the duplexer uses, as a pass band, a fixed frequency band including the first transmit band and the second transmit band. A receive filter unit of the duplexer uses, as a pass band, a fixed frequency band including the first receive band and the second receive band.