Membership in the Japan Society for Dying with Dignity rose by 8,913 in fiscal 2006, the fourth-largest increase since it was founded in 1976, according to the group.
The rise is being attributed to growing interest in end-of-life care after a hospital in Imizu, Toyama Prefecture, was found to have taken a patient off a respirator last year.
Membership reached 118,615 at the end of March.
"In recent years, 8,000 to 10,000 people have joined our society annually, while about 6,000 have died or left us," said Masafumi Takai, the society's secretary general. "Therefore, the actual increase has been some 2,000 to 4,000 people."
In fiscal 2005, an average of 770 people joined per month. But since March 2006, when the Imizu incident was reported, the society has been flooded with inquiries and membership applications.
That April, some 2,900 people joined, and a month later the number was about 2,600.
"We couldn't keep up with membership procedures," Takai said.