A multiplexer (10) includes a common terminal (100c), a filter (21) that supports Band 41, a filter (22) that supports Band 40, and a filter (23) that supports Band 1Rx. A matching circuit (11) includes a capacitor (C1) connected in a path (111), a switch (SW1) connected between a ground and a node in the path (111) between the capacitor (C1) and the filter (21), a resonant circuit connected in a path (112) and having a resonant frequency in Band 40, the resonant frequency being a frequency at which an impedance is minimum, a switch (SW2) connected between the ground and a node in the path (112) between the resonant circuit and the filter (22), an inductor (L1) connected in a path (113), and a switch (SW3) connected between the ground and a node in the path (113) between the inductor (L1) and the filter (23).