The Japan Organ Transport Network said Tuesday 15.7 percent of people recently surveyed said they have declared their will on whether or not they wish to donate their organs after brain death or cardiac death.
The figure is higher than the 11.1 percent a year earlier, but the nation's only body arranging organ transplants between donators and recipients said the proportion still remains low.
At issue is how well the public has been informed on donating organs since a major legal revision took effect in 2010.
Since the revised law came into force, Japanese hospitals have performed 138 organ transplant operations from donors who were declared brain dead.
Among them, only 20 percent were found to have expressed their will to donate their organs if they were declared brain dead. In the rest of the cases, family members had consented to the donations.
The network surveyed people between their teens to 60s across the country over the Internet in March. A total of 1,000 people responded.
Questions included whether they knew if they can declare their will through means including a donor card, driver's license and health insurance card, as well as their views on organ donations in general.
Nearly 70 percent of those who have yet to express their will on the issue replied that they do not wish to donate their organs, saying they feel uncomfortable about the concept, or are unsure whether they want to donate or not.
Of those who said they have already declared their will or are thinking of doing so, 65 percent replied that they would donate their organs in the event of either brain death or cardiac death, up from 60.7 percent a year earlier.
The survey found that 36.8 percent of respondents had discussed the issue of organ donation with family members, down from 39.3 percent a year earlier.