A court in Japan has ordered Kansai Electric Power to shut down two of its reactors in Takahama, western Japan.
The Otsu District Court ruling came after complaints by local residents about the safety of the plant.
It comes ahead of the fifth anniversary of the earthquake and tsunami that led to the Fukushima nuclear disaster.
Japan gradually shut down all the country's nuclear plants after the accident but some have now been allowed to restart, despite public unease.
The Takahama plant has been told to shut immediately, local media reported, saying this is the first ruling issued in Japan against an operating nuclear plant.
The company says it will quickly appeal against the ruling.
Of the two reactors ordered to shut down, only the No 3 reactor is currently running. The No 4 reactor was taken offline last month after a technical problem just days after it restarted.
Only two other reactors, in Sendai, have been allowed to operate again in Japan under new safety rules.
The meltdown at Fukushima happened after the plant was hit by a tsunami triggered by a powerful earthquake in March 2011.
It was the worst nuclear accident since the Chernobyl disaster in 1986.
Almost 16,000 people died and more than 2,500 are still listed as missing. None of the deaths, however, have been linked to the nuclear disaster, although there were a number of deaths in the subsequent evacuation.