The 1,421 metre high volcano, located in Kirishima mountain range, spewed plumes of smoke and volcanic ash some 2,100 metres from its crater.
Shinmoedake, in a largely rural area some 985 km (616 miles) from Tokyo on Japan's southernmost main island of Kyushu, had been erupting on a smaller scale since March 1, when entrance to the 1,421 metre-high peak was restricted.
The Japan Meteorological Agency gave the volcano a level three eruption warning, indicating that the public should not approach the volcano but that there was no immediate need to evacuate as would be the case with a level five warning.
The meteorological agency said the volcanic activity was expected to continue.
The agency also warned about the possibility of pyroclastic flows within a similar distance from Mt. Shinmoe's crater, as well as falling ash and broken glass if there's a subsequent powerful explosion which causes an air shock. All flights passing to and fro from the nearby Kagoshima airport were cancelled since the volcano was still in eruption mode.
Japan, which sits on the Pacific "Ring of Fire", has 110 active volcanoes and is prone to earthquakes and volcanic eruptions.
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