[en] JRR-3 has been continuing its stop state for more than 5 years as of FY2015 after stopping the use operation of the reactor in November 2010. Different responses are required in the maintenance management for operation resumption, compared with those in normal operation. This paper introduces part of the maintenance managements that are performed during long-term stop. The water qualities of primary coolant and secondary coolant are controlled by measuring pH and conductivity, and the prevention of crevice corrosion of equipment is performed. In the management of pumps for coolant circulation, vibration measurement is performed to confirm that there are no signs of abnormality. As the management of the core structure, the bend measurement of beryllium reflector is performed to confirm that there is no hindrance to operation resumption, and the visual inspection of high burnup fuel elements is performed to confirm that abnormality has not occurred. As for the management of monitoring equipment, the equipment required in shutdown period is subjected to calibration work, and the equipment required in operation period is subjected to soundness check based on the results of cooling system operation. As the functional maintenance of the cooling system, cooling system operating test and 10-day continuous operation of the cooling system are monthly performed to confirm the soundness of equipment. In addition, the competence maintenance and capacity improvement of operators are performed through the cooling system operation and reactor simulator training. (A.O.)