The leaders of India, Brazil, South Korea, and other non-G7 nations invited to the summit visited the Hiroshima Peace Memorial Museum on Sunday.
On the final day of the G7 summit, the leaders were guided by Japanese Prime Minister Kishida Fumio during their 40-minute visit.
The leaders are believed to have seen exhibits and written comments in the book of condolences.
They later offered flowers and prayers to a cenotaph dedicated to atomic bomb victims.
The G7 leaders made an earlier visit to the museum on Friday. The visits were part of Kishida's efforts to give momentum to nuclear disarmament and non-proliferation by having the leaders of nuclear powers look first-hand at the terror and devastation caused by atomic bombing.