A mixer includes a storage portion, a reception portion, a user-definition-scene-memory setting portion, a setting changing portion, a storage processing portion, and a recall processing portion. The reception portion receives specification of several parameters among a plurality of parameters. The storage portion stores setting values of the plurality of parameters. The user-definition-scene-memory setting portion stores the several parameters, received by the reception portion, in the storage portion for every scene as a user-definition-scene-memory. The setting changing portion receives an operation of changing current setting of the plurality of parameters. The storage processing portion stores setting values of the several parameters, changed in the setting changing portion, in the current data storage portion. The recall processing portion calls setting values of the several parameters corresponding to the user-definition-scene-memory from the storage portion, when a recall of the user-definition-scene memory is received in the reception portion.