"I strongly demand that they not be harmed and that they be immediately released," he told a news conference during a visit to Jerusalem. "I am extremely indignant at such an act."
IS has threatened to kill the two Japanese hostages unless it receives a USD 200 million ransom within 72 hours, but Abe vowed not give in to "terrorism".
"The international community will not give in to terrorism and we have to make sure that we work together," Abe said as he wound up a Middle East tour and prepared to fly home.
Abe was to make the short drive from Jerusalem to visit Palestinian president Mahmud Abbas in the West Bank city of Ramallah before cutting short his tour to fly home to Japan.