A volume adjustment device comprising: a display section ; a touch panel that is linked with the display section ; and a controller being configured for: displaying a slide bar including: a normal area having an upper limit, a limit area having a lower limit, the lower limit of the limit area coinciding with the upper limit of the normal area, and a knob indicating volume value on the display section ; receiving movement of a detected contact on the touch panel as a movement of a target , the target being a movement goal position of the knob ; adjusting volume of an audio signal to volume value corresponding to a position of the knob ; moving the knob , within the normal area in which the knob is free to move, at the same speed as the speed of the received movement of the target , when the controller receives movement of the target within the normal area; when the target is moved into the limit area and the knob reaches the lower limit of the limit area: moving the knob at a predetermined speed towards the target , and expanding the normal area towards the limit area at an expansion speed, wherein the predetermined speed is the same as the expansion speed. a display section ; a touch panel that is linked with the display section ; and a controller being configured for: displaying a slide bar including: a normal area having an upper limit, a limit area having a lower limit, the lower limit of the limit area coinciding with the upper limit of the normal area, and a knob indicating volume value on the display section ; receiving movement of a detected contact on the touch panel as a movement of a target , the target being a movement goal position of the knob ; adjusting volume of an audio signal to volume value corresponding to a position of the knob ; moving the knob , within the normal area in which the knob is free to move, at the same speed as the speed of the received movement of the target , when the controller receives movement of the target within the normal area; when the target is moved into the limit area and the knob reaches the lower limit of the limit area: moving the knob at a predetermined speed towards the target , and expanding the normal area towards the limit area at an expansion speed, wherein the predetermined speed is the same as the expansion speed. displaying a slide bar including: a normal area having an upper limit, a limit area having a lower limit, the lower limit of the limit area coinciding with the upper limit of the normal area, and a knob indicating volume value on the display section ; a normal area having an upper limit, a limit area having a lower limit, the lower limit of the limit area coinciding with the upper limit of the normal area, and a knob indicating volume value on the display section ; receiving movement of a detected contact on the touch panel as a movement of a target , the target being a movement goal position of the knob ; adjusting volume of an audio signal to volume value corresponding to a position of the knob ; moving the knob , within the normal area in which the knob is free to move, at the same speed as the speed of the received movement of the target , when the controller receives movement of the target within the normal area; when the target is moved into the limit area and the knob reaches the lower limit of the limit area: moving the knob at a predetermined speed towards the target , and expanding the normal area towards the limit area at an expansion speed, wherein the predetermined speed is the same as the expansion speed. moving the knob at a predetermined speed towards the target , and expanding the normal area towards the limit area at an expansion speed, wherein the predetermined speed is the same as the expansion speed. <EOS>