TOKYO — Sumiteru Taniguchi, who survived the atomic bombing of Nagasaki as a teenager and went on to become a leading advocate for nuclear disarmament, died on Wednesday in Nagasaki. Overcoming a lifetime of debilitating pain and radiation-related illnesses, he lived to 88.

The cause of death was duodenal papilla cancer, according to Fumie Kakita, secretary general of the Nagasaki Atomic Bomb Survivors Council.

Mr. Taniguchi was one of about 165,000 remaining survivors — known in Japan as hibakusha — of the nuclear bombings in Hiroshima and Nagasaki. With their average age now over 81, their voices are dying out.

“After I received the news of his death, I realized the era when there are hibakusha is getting closer to the end,” Tomihisa Taue, the mayor of Nagasaki, told NHK, the public broadcaster. “I think we can truly show our gratitude to Mr. Taniguchi when I can pass on the baton of his wish, which is that the same thing never happens again, and that there will be no more hibakusha.”