A record low 17.7 percent of all employees were unionized as of June 30, down 0.2 percentage point from a year earlier, according to an estimate by the Ministry of Health, Labor and Welfare.
It's the third straight year the figure has declined and the lowest level since the survey began in 1947, the ministry said. Union membership fell by 17,000 from a year ago to 9,875,000.
There were 914,000 part-time workers in unions, or about 6.5 percent of the total, the highest rate since they were added to the survey in 1990.
It's estimated that unions in the manufacturing sector, the largest force among unions, lost 33,000 members in the year. In contrast, unions in the hotel and food-servicing industry increased membership by 17,000.