Japanese officials ordered evacuations on Tuesday afternoon, local time, after raising the volcano threat alert for Mount Hakone on Honshu, the country's main island.
The Level 2 alert, which was issued in early May, was raised to a Level 3, urging residents to not approach the volcano after volcanic ash was reported coming from it, the Japanese Meteorological Agency and national broadcaster NHK reported.
The JMA called it a "small-scale eruption."
The last major eruption of Mount Hakone occurred around 2,900 years ago, according to the Global Volcanism Project at the Smithsonian Institution.
Mount Hakone is 1,438 meters (4,717 feet) high.
The volcano is located southeast of Mount Ontake, the site of a deadly eruption in September 2014.