More single people in their 20s say they don't want any children, think it's costly and exhausting to raise them, and show little interest in kids in general, according to a new survey.

The findings, released by the Health, Labor and Welfare Ministry on Wednesday, are based on a poll of 12,284 people, single and married, aged 21 to 30 in 2013, in comparison with a survey of 18,820 people in the same age group in 2003.

It found that 15.8 percent of single men surveyed in 2013 said they want no children, up from 8.6 percent 10 years earlier.

Of the single women surveyed, 11.6 percent said they don't want any children, compared with 7.2 percent a decade ago.

The 2013 survey also asked single people's views on children and child-rearing. Among men who replied they didn't want any children, 39.8 percent said they "had no views" on children, a stance shared by only 4.4 percent of men who said they want to have kids.

"The fact that this many men said they had no views on children was surprising to us," a health ministry official in charge of the survey said Friday. "I think it reflects their disinterest in children in general."

Meanwhile, 29.6 percent of single men who did not want any kids said they felt rearing children and paying for their education would be costly; 29.3 percent said they feared that having children would cut into their free time; and 16.9 percent said they would be physically and mentally exhausted from child-rearing.

In contrast, the percentage of married men who said they want three children or more has increased to 46.2 percent in 2013 from 31.4 percent in 2003. The ratio was 47.4 percent for married women in 2013, up from 30.4 percent in 2003.

The health ministry attributed the changes to more companies allowing couples to take child care leave and dads spending more time doing housework.