Tokyo Electric said the worker's death is not linked with his work at the plant, citing results of medical examination by doctors.
The man had been exposed to 0.5 millisievert of radiation at the plant and showed no internal exposure to radiation, said the power company, known as TEPCO.
The dosage is much smaller than 5 millisieverts or higher per year -- the benchmark for recognizing a death as work-related -- TEPCO said, citing the Ministry of Health, Labor and Welfare's criteria on work-related deaths. The ministry's criteria also put the incubation period to develop symptoms of acute leukemia at one year.
TEPCO said the man had been involved with duties on radiation control at the plant for a week starting in early August. He later complained of poor health and underwent medical checkups before his death.
The utility said it had no information on the man's work career before being engaged in the recovery work at the nuclear power plant which was crippled by the March 11 earthquake-tsunami disaster.