A multiplexer through which different frequency bands pass, including: a housing that includes an I/O terminal and a channel group which inputs and/or outputs frequencies of different ranges, includes a plurality of connectors, and is separated from the I/O terminal; a low-pass filter provided inside the housing, electrically connected to the I/O terminal, and formed of a distributed constant type; a common capacitor provided in parallel to the low-pass filter and electrically connected to a contact point between the I/O terminal and the low-pass filter; and a cavity filter which includes a plurality of cavities which are formed in the housing and a resonator which is respectively installed in the cavities.