Mr Abe and his wife Akie laid flowers and offered silent prayers at the memorial in Wewak on Papua New Guinea's northern coast.
Friday's visit was the first by an incumbent Japanese prime minister to the memorial, which was built by the Japanese Government in 1981.
Japan wants to be a country that thinks about peace with its friends in Asia and around the world.
Japanese Prime Minister Shinzo Abe
The Aitape-Wewak campaign was one of the final campaigns in the Pacific theatre of World War II.
About 200,000 Japanese soldiers were killed in the New Guinea campaign.
"We must not repeat the horrors of the war," Mr Abe told reporters.
"I pledged in front of the spirits of the war dead that Japan wants to be a country that thinks about world peace with its friends in Asia and around the world."
The Japanese premier also said he would strive to bring back the remains of Japanese soldiers who died in the Pacific or other areas during the war.
Gas exports, aid top Abe agenda
Mr Abe's visit - the first by a Japanese prime minister since 1985 - is focused mostly on business ties, in particular PNG's multi-billion dollar liquid natural gas exports to Japan.
Papua New Guinea's Prime Minister Peter O'Neill, who travelled to Tokyo in June to welcome the first LNG shipment, said the project would support his nation's economic and social development.
Mr Abe said Japan was committed to offering further development assistance to the impoverished nation.
"I would like to express my willingness to support the further development of Papua New Guinea in the future," he said.
"I also would like to express Japan's determination to even more actively contribute to ensuring peace, stability and prosperity in the international community including the Pacific regions, together with the people and the government of Papua New Guinea."
Mr Abe's two-day visit is also seen as a deepening of links to the Pacific, as China exerts its influence in the region.
Papua New Guinea is the last leg of a three-nation trip that has also included official visits to New Zealand and Australia.
Mr Abe, who was joined by a 150-strong business delegation in PNG, is scheduled to fly back to Japan on Saturday.