A diplexer module includes substrates, an external connection terminal, a first diplexer including a first transmission filter and a first reception filter, a second diplexer including a second transmission filter and a second reception filter, and a switch. The external connection terminal is connected to the switch, the switch is connected to the first diplexer and the second diplexer, and the first transmission filter, the second transmission filter, the second reception filter, and the first reception filter are aligned in this order when the substrates are seen in plan view from above.