A knife-wielding black-clad figure, standing in a desert area along with two men and wearing orange clothing, criticised what he called the Japanese government's support for a US-led coalition waging a military campaign against Islamic State.
The threat comes after Japan's Prime Minister Shinzo Abe pledged to extend $200 million to countries fighting the terrorist group.
A spokeswoman from the Foreign Office said:
"We are aware of the video and we are studying the content."
Japanese officials have not made any immediate comment on the latest video.
