In a thermal development apparatus provided with a drum to heat a thermally developable material on an outer circumferential surface thereof while rotating at a predetermined constant rotation speed; a feeding device which feeds a sheet-like thermally developable material onto the outer circumferential surface of the drum, whereby the thermally developable material fed by the feeding device is thermally developed by being heated while being held on the outer circumferential surface of the drum; the feeding device feeds each of thermally developable materials to the drum with a timing to shift a position of a leading end of each of thermally developable materials to be held on the drum into a rotation direction of the drum with the shortest time interval Tmin or longer among the thermally developable materials fed onto the drum so as to be continuously heated by the drum.