The trend has been largely blamed on a widespread belief, especially in rural Japan, that women who give birth should quit their jobs, amid shortages of childcare centres and other systemic factors.
Japan's population has already started to decline as younger people delay starting a family due to the perceived burden on their finances, lifestyles and careers.
A growing population of elderly, known for their longevity, is meanwhile overwhelming a welfare system that is decreasingly supported by a shrinking workforce, meaning that tax revenue is declining.
Collectively, the survey found all age categories showed a general lack of interest toward sex, except for men in their 30-34 years of age with just 5.8 percent of these respondents not interested, as opposed to 8.3 percent in 2008.
The survey also found that 40.8 percent of married people said they had not had sex in the past month, up from 36.5 percent in the 2008 survey and 31.9 percent in the 2004 survey.
Nearly 50 percent of married people older than 40 years old said they have not had sex in the past month, the study said.
Among reasons for not having sex, survey participants cited vague reluctance after childbirth, that they could not be bothered, or that they were too tired after work, it said.
The survey, conducted by a team of experts commissioned by the health ministry, received valid answers from 671 men and 869 women in interviews.
It was originally designed to gauge the success of Japan's birth control education with an aim to reduce unwanted pregnancies, Kitamura said.
But the falling abortion rate may be a result of a general indifference toward sex and not attributable to the success of sex education, he said.
Source-AFP