The city said that given the significance of the 75th anniversary of the bombing, that killed 140,000 people before the end of 1945, they had decided to hold the ceremony despite the spread of coronavirus, but with strict precautions in place.
Prime Minister Shinzo Abe attended as usual, but the number of foreign visitors was down.
Overall attendance was scaled back to less than 10 percent of usual, with chairs spaced far apart and most attendees wearing masks.
Thousands usually pack the Peace Park in central Hiroshima to pray, sing and lay paper cranes as a symbol of peace, entrance was sharply limited and only survivors and their families could attend the memorial ceremony itself.
At 8:15 a.m. on Aug 6, 1945, U.S. B-29 warplane Enola Gay dropped a bomb nicknamed "Little Boy" and obliterated the city, killing 140,000 of an estimated population of 350,000, with thousands more dying later of injuries and radiation-related illnesses.