The survey, conducted in September, also showed more married couples were also found sexless than before, with more than 40 percent saying they had no sex in the past month.
The last survey was conducted by a research group of the Health, Labor and Welfare Ministry to study people's views on lifestyle. It is based on replies provided by 671 men and 869 women aged 16 to 49 in interviews.
"The survey result confirmed that young men have become 'herbivorous'," said Kunio Kitamura, head of the Clinic of the Japan Family Planning Association who took part in the survey, using the term used increasingly in Japan to describe young males who are shy and passive in relationships with women.
According to the ministry, 35.1 percent of men aged 16 to 19 said they are uninterested in or averse to sex, surging from 17.5 percent in the previous poll in 2008.
The percentage climbed to 21.5 percent among men aged 20 to 24 from 11.8 percent two years earlier, and among women of any age group, the survey showed.
Those married men and women who said they had no sex in the past month totaled 40.8 percent, up from 36.5 percent in the previous survey and 31.9 percent in a 2004 study.
Respondents cited vague reluctance after childbirth, a sense that it is a bother and job-related fatigue as reasons for shunning sex with their partners.
"Some measures are necessary (to deal with the increase in sexless couples) as it is directly linked to the declining birthrate," Kitamura said.