In March 2015, we observed mating behavior of loggerhead turtles in the western coastal waters of Okinawa Island, Japan. Two males and one female were initially involved, of which one of the males (M1) was attempting to mount the other male (M2) that had already mounted the female. Shortly after the onset of observation, M1 dismounted from M2 and swam away. At that time, the female, initially seemingly resisting copulation with M2, became receptive. This is the first report of loggerhead turtle mating behavior that involves more than two individuals. This observation suggests that the mating season of loggerheads around Okinawa Island includes the early spring.