To manufacture a lot of refined individual trays of respective patients in a short time.

At the time of molding a tray body (A) from tray resin, the base part of a handle (B) molded beforehand from synthetic resin is attached to the tray body (A) in buried state. A tip part or a middle part where the handle (B) is projected from the tray body (A) and exposed is received and supported from below by a supporting leg (C) for the handle only until the tray resin of the tray body (A) is hardened. After the tray resin is hardened, the supporting leg (C) is moved from the handle (B).