Police sealed off the popular Chirihama beach in Hakui, Ishikawa Prefecture, on the Sea of Japan coast Sunday after a stroller found a naval mine, police and the Maritime Self-Defense Force said.
Staff from the MSDF's Maizuru district headquarters said the mine, apparently used for training purposes, no longer contains gunpowder and does not pose a threat, but added that they will examine it further.
The rusty mine is about 90 cm wide with letters and numbers on it, police said.
Chirihama beach features the 8-km Nagisa Driveway, where motorists can drive along the sandy beach.