The Justice Ministry said the executions were carried out early Thursday at three locations. One of the condemned inmates killed a schoolgirl.
Japan's last execution was in September. It now has 134 inmates on death row. Executions in Japan are done by hanging.
Capital punishment in Japan has been widely criticized by human rights groups though polls show the public supports it. Japan's government releases few details about executions and inmates are generally not informed of their pending execution until immediately before it is carried out.