A control rod drive attaching and detaching device and a control rod drive handling device are mounted on a revolving device to be movable independently from each other. The control rod drive attaching and detaching device includes bolt handling means for loosening and tightening bolts for fastening a control rod drive to a pressure vessel of a nuclear reactor, coolant splash preventing means for disposing of coolant which flows from the control rod drive when the latter is detached from the pressure vessel, and uncoupling means for uncoupling a control rod from the control rod drive. The control rod drive handling device includes a column pivotally mounted on a carriage, a cart removably mounted on the column, and means for moving the column to a horizontal position. Each control rod drive mounted to the pressure vessel of the nuclear reactor is detached from the pressure vessel by the control rod attaching and detaching device and transferred to the cart of the control rod drive handling device. The column is moved to a horizontal position, and the cart with the control rod drive supported thereon is removed from the column.