A treatment instrument operation unit is provided with a drive unit, an operation portion installation section and a command signal output section. The drive unit drives an operation portion for operating each treatment section of the respective treatment instruments. The operation portion is attached to the operation portion installation section provided to the drive unit. The command signal output section outputs an installation start signal to a controller for notifying that the installation of the treatment instrument has begun upon installation of the operation portion in the operation portion installation section. After outputting the installation start signal from the command signal output section to the controller, the drive unit is driven based on the control signal outputted from the controller to move the operation portion installation section to the position where the operation portion is allowed to be installed.
