The facility for elderly welfare recipients in the city of Sapporo was completely engulfed in the fire that broke out late in the evening when the building is usually unstaffed.
Eleven people were killed and five were rescued in a fire at a facility to support senior people on welfare in northern Japan late on Wednesday, public broadcaster NHK said.
Three of the survivors, aged between their fifties and eighties, were being treated in hospital but their condition was not life-threatening, the broadcaster said.
The 16 elderly people were living in the three-storey wooden facility in Sapporo, where they paid a monthly rent of 36,000 yen ($330), NHK said on Thursday.
The facility is aimed at supporting elderly people with financial difficulties by offering low-cost accommodation and helping them find work.
Television footage showed the three-storey building engulfed in flames and dozens of firefighters battling the blaze in snowy conditions.
Pictures of the aftermath showed the blackened husk of the building, whose roof had apparently collapsed due to the fire.
The fire sparked memories of a similar incident in Sapporo in 2010 when seven residents of a private nursing home for the elderly were killed in a pre-dawn fire.
Four women and three men aged in their 60s to their 80s died when the blaze swept through the two-storey wooden house.