The lawsuit had been filed by 141 South Korean victims of the US dropping of atomic bombs on Hiroshima and Nagasaki, for which they demanded 10 million won (about $9,000) per person from their government, Xinhua news agency reported.
A Seoul court ruled that the government's actions were not sufficient for the victims, but said it was making diplomatic efforts to secure damages from Japan.
About 70,000 South Koreans, who forcibly or voluntarily moved to Japan during the 1910-45 Japanese colonial rule of the Korean peninsula, were victimised during the bombings.
The South Korean victims failed to receive proper cure and rewards from either the South Korean or the Japanese governments, dragging down their survival rate to about 3.5 per cent -- much lower than the Japanese surviving rate of 30 per cent.
South Korea's constitutional court in August 2011 ruled that the government should make efforts to help the atomic bomb victims in securing damages from the Japanese government.
Two years later, 79 victims filed a damages claim lawsuit against the South Korean government, but the court dismissed the suit in June last year.
