The photograph, apparently uploaded to the Internet late on Sunday, showed a bearded man dressed in orange holding a hand-written sign in Japanese.
"Please help me. This is my last chance," said the sign, written in shaky characters and signed "Jumpei Yasuda."
Yasuda's plight came to attention in March, when a video surfaced showing him reading a message to his country and his family. Japanese media said he was capture by a group called Nusra Front after entering Syria from Turkey last June.
Foreign Minister Fumio Kishida said the government was analysing the new photo and believed it was Yasuda, while Chief Cabinet Spokesman Yoshihide Suga said the government was doing what it could.