The activity was so powerful the city of Kagoshima on Kyushu Island, about 5 miles from the volcano, remained coated with ash, the Japan Meteorological Agency said.
Residents in the city were forced to wear masks because of the ash.
Kyodo News reported the eruption began about 4:30 p.m. local time. Besides ash, which reached a height of up to 5,000 meters or more than 16,400 feet, the volcano also tossed out large rocks. The report said a lava flow of more than a half mile in length also was observed.
There were no reports of injuries.
In Kagoshima, train operators halted service temporarily to remove ash and rocks from the railroad tracks.
Meteorologists said the ash plume was the highest from the volcano's Showa vent since it became active in June 2006. The Sunday eruption was the volcano's 500th this year, Kyodo reported.
Experts did not rule out similar eruptions in the future.