Numerous people gathered at Peace memorial park, Nagasaki to remember people who died instantly in the blast, or of the after-effects in the months and years after the bombing, which hit Nagasaki on August 9, 1945.
The nuclear bombings destroyed both Hiroshima and Nagasaki cities and claimed at least 2 lakh lives while many succumbed to injuries and illness in later days.
Since then, Nagasaki Day is commemorated every year on August 9 with the prime focus on anti-war and anti-nuclear discussions and demonstrations.
The bombing of Nagasaki came three days after the first-ever atomic blast at Hiroshima, which claimed about 140,000 lives in all. Hiroshima held its own remembrance ceremonies earlier this week.
Despite the public's safety concerns about nuclear energy since the Fukushima crisis, Japan Prime Minister Shinzo Abe has been aggressively pushing to export nuclear plants and technology to emerging countries, including Turkey and Vietnam, and trying to step up cooperation with France and India.
(with agency inputs)