He pointed out that he came from the only country ever to have been hit by the atomic bomb.
Amano was chosen by the IAEA's 35-member board of governors, its main decision-making body, in July. But his appointment had to be adopted by all member states.
The change in leadership comes at a crucial time for the agency.
Little progress has been made with North Korea in recent months. India and Pakistan appear unlikely to sign the Non-Proliferation Treaty. Israel refuses to even discuss its atomic arsenal and the agency is not in a position to ascertain the true nature of Iran's nuclear programme.
However, Iran and six major world powers agreed to hold talks on October 1 at a still unspecified venue to try to resolve the long-running standoff.
When questioned about his policy priorities, Amano refused to make any concrete statements.
"I'm not yet responsible for the operation," he said, pointing out that ElBaradei was still in charge", he said.