Amano touted the safety of nuclear power more than a year after a meltdown at the Fukushima Daiichi power plant in Japan.
Japan in May shut its last operating nuclear reactor for maintenance, leaving the country without nuclear power for the first time in more than 40 years. By June, Japanese Prime Minister Yoshihiko Noda gave approval for the restart of the Ohi nuclear power facility despite national protests.
Eighteen months after the (Fukushima) accident, it is clear that nuclear energy will remain an important option for many countries, Amano said at during the International Atomic Energy Agency's regular meeting in Vienna.
"Our latest projections show a steady rise in the number of nuclear power plants in the world in the next 20 years."
Most of that growth would come from Asian economies, he said. Lessons learned from the Fukushima disaster, he added, would drive nuclear energy policies moving forward.
"The most important lesson that we have learned from Fukushima Daiichi is that we need a much more intense focus on nuclear safety," he said.
An 11-mile exclusion zone is in place around the plant, which suffered the worst nuclear disaster since the 1986 meltdown at the Chernobyl plant in Ukraine.
Dennis Rodman pledges to end trips to North Korea
Susan Sarandon 'very excited' about daughter's pregnancy