Critics have accused the U.S. and Japan of calling for an end to atomic weapons, but using foreign policies based on nuclear deterrence.
“I believe he is not apologizing to leave the possibility open to use nuclear weapons in the future,” said Yohei Sakube, a protester at the Peace Memorial Park.
The protesting group included students, farmers, labor union leaders and residents. Their posters said "You're not welcome here, Obama."
The White House said the reason for the visit is not to apologize to Japan or to revise the country’s decision to use the atomic bomb. Instead, he will talk about the need to eliminate the risk of nuclear weapons.
Obama, who won the 2009 Nobel Peace Prize for nuclear disarmament, says he will only honor those who died in World War II. The atomic bombing of Hiroshima and Nagasaki at the end of World War II killed close to 200,000 people.
Obama will become the first U.S. president to visit Hiroshima.