It is assumed by Shakyamuni Nyorai or Dainichi Nyorai (the Great Sun Buddha) (in Taizokai) formed by the right hand put on top of the left hand with the tips of both thumbs put together and other fingers stretched.
釈迦如来、大日如来（胎蔵界）の定印は左手の上に右手を重ね、両手の親指の先を合わせて他の指は伸ばす。