Those going to the December 10 ceremony will include group co-chair Terumi Tanaka, 92, who witnessed the 1945 Nagasaki bombing as a child, as well as other survivors and their children.
With money provided by the Nobel Committee not enough to cover the travel expenses of such a large delegation, the group launched a crowd-funding campaign, which has so far raised over 36 million yen ($240,000).
Hidankyo member Jiro Hamasumi, 78, told reporters on Monday that the group was "very surprised" that the campaign raised 10 million yen on the first day alone.
"I'm delighted to say that our delegation will be able to go," Hamasumi said.
He was in his mother's womb when the United States dropped the first atomic bomb on Hiroshima on August 6, 1945.
His father, who was at work just a few hundred metres (yards) from the epicentre, was killed.
"I hope I can speak from my own experience (in Oslo) about our desire not to see another victim, and that nuclear weapons must never be used," Hamasumi said.
The grassroots anti-nuclear organisation was established in 1956 and is the only nationwide association of A-bomb survivors, who are known as hibakusha.
The Norwegian Nobel Committee nominated Nihon Hidankyo "for its efforts to achieve a world free of nuclear weapons and for demonstrating through witness testimony that nuclear weapons must never be used again".
Around 140,000 people died in Hiroshima and 74,000 others in Nagasaki three days later on August 9, 1945.
Survivors suffered from radiation sickness and longer-term effects including elevated risks of cancer.
The bombings, the only times nuclear weapons have been used in history, were the final blow to imperial Japan and its brutal rampage across Asia. It surrendered on August 15, 1945.
