Harold Camping of Family Radio said in a message on his network's website that "when it comes to trying to recognize the truth of prophecy, we're finding that it is very, very difficult."
The 90-year-old had earlier predicted the world would end on May 21. Some listeners sold their belongings to help pay for billboards spreading his doomsday message.
Camping said since his failed prediction, he and believers are "learning to walk more and more humble before God."
The Associated Press contributed to this report.