A mute detachably attached to a brass instrument includes a fixed part and a plurality of branch pipes, each including a main pipe and an auxiliary pipe. The branch pipes are unified together and inserted into a bell pipe of a brass instrument. The fixed part is attached to the tapered portion of a bell pipe and interposed between the interior of the bell pipe and the exterior of the main pipe. The branch pipe is designed such that the auxiliary pipe is connected to the main pipe at an interconnect part, at which an air flow propagating through the main pipe is partly branched into the auxiliary pipe.