An operation device comprising: a plurality of operation sections to each of which is allocatable, as an operation target, any one of a plurality of signal processing channels, the plurality of the operation sections being arranged in a row on an operation panel, each of said operation sections being capable of setting, at a desired value, a parameter to be used for processing a signal of the signal processing channel allocated thereto, the value of the parameter set for each of said operation sections being stored into a memory in association with the allocated signal processing channel, wherein said operation device further comprises: a plurality of first notification sections associated with individual ones of the operation sections, each of the plurality of first notification sections being configured to notify first information about the signal processing channel allocated to the associated operation section; a plurality of second notification sections associated with individual ones of the operation sections, each of the plurality of second notification sections being configured to notify second information indicative of the value of the parameter to be used in the signal processing channel allocated to the associated operation section; a reception section configured to receive a user's instruction for switching signal processing channels that are to be allocated to individual ones of the operation sections, characterized by said reception section being configured to continuously receive the instruction in a form of a user's slide operation along a direction traversing the row of the plurality of the operation sections on the operation panel, the signal processing channels to be allocated to the respective operation sections being varied with the continuous user's slide operation; a first update section (10, S2) configured to, while said reception section is continuously receiving the instruction, dynamically update the first information, notified by all of the plurality of first notification sections, in response to the instruction in such a manner that the plurality of first notification sections notify the first information about the signal processing channels to be allocated to the plurality of operation sections and maintain, without updating, the second information notified by the plurality of second notification sections; and a second update section (10, S4, S5) configured to, upon completion of the instruction having been continuously received by said reception section, determine signal processing channels to be allocated to individual ones of the plurality of operation sections in conformity with the signal processing channels responsive to the instruction completed and update the second information, notified by all of the plurality of second notification sections, with the values of the parameters corresponding to the signal processing channels having been determined to be allocated to the plurality of operation sections. a plurality of first notification sections associated with individual ones of the operation sections, each of the plurality of first notification sections being configured to notify first information about the signal processing channel allocated to the associated operation section; a plurality of second notification sections associated with individual ones of the operation sections, each of the plurality of second notification sections being configured to notify second information indicative of the value of the parameter to be used in the signal processing channel allocated to the associated operation section; a reception section configured to receive a user's instruction for switching signal processing channels that are to be allocated to individual ones of the operation sections, characterized by said reception section being configured to continuously receive the instruction in a form of a user's slide operation along a direction traversing the row of the plurality of the operation sections on the operation panel, the signal processing channels to be allocated to the respective operation sections being varied with the continuous user's slide operation; a first update section (10, S2) configured to, while said reception section is continuously receiving the instruction, dynamically update the first information, notified by all of the plurality of first notification sections, in response to the instruction in such a manner that the plurality of first notification sections notify the first information about the signal processing channels to be allocated to the plurality of operation sections and maintain, without updating, the second information notified by the plurality of second notification sections; and a second update section (10, S4, S5) configured to, upon completion of the instruction having been continuously received by said reception section, determine signal processing channels to be allocated to individual ones of the plurality of operation sections in conformity with the signal processing channels responsive to the instruction completed and update the second information, notified by all of the plurality of second notification sections, with the values of the parameters corresponding to the signal processing channels having been determined to be allocated to the plurality of operation sections.