The volcano in North Sumatra province started belching ash and volcanic material at 9 am and the eruption lasted almost six minutes, a local geological agency said.
Images showed a thick column of ash spewing from the inside of Sinabung towards the east.
No evacuation orders have been issued, and there has been no reported flight disruption.
Authorities have instructed residents to avoid a five-kilometre radius around the crater, a zone that has been left unoccupied for years as volcanic activity increased.
"Residents and tourists should not do any activity around Mount Sinabung or relocated villages because the volcanic activities remain high," Muhammad Nurul Asrori, an official at Mount Sinabung monitoring post told AFP, adding that the volcano alert status remains unchanged at level three.
Sinabung, a 2,460-metre (8,070-foot) volcano, was dormant for centuries before roaring back to life in 2010 when an eruption killed two people.
After another period of inactivity, it erupted again in 2013 and has remained highly active since.
Indonesia -- an archipelago of more than 17,000 islands and islets -- has nearly 130 active volcanoes.
It sits on the "Ring of Fire", a belt of tectonic plate boundaries circling the Pacific Ocean where frequent seismic activity occurs.
