Problem to be solved: To provide a drying tray which can reduce the cost of a drying tray, shorten the drying tray mounting process of a release sheet, and improve the quality of a dried food material sheet, Solution: The method for manufacturing the raw material for a liquid-tight container includes the steps of: Preparing a raw material containing a liquid-tight container; and drying the raw material. Solution: A release sheet 2 is placed on a U-shaped tray 1 with both ends of the side surface of a flat plate raised so as to cover the inside of the U-shaped tray, two removable partition plates 3 are placed on both ends of the U-shaped tray which are not raised, The liquid raw material is adhered to the partition plate and dried, so that the partition plates are adhered to both ends of the product and pulled together to eliminate shrinkage...
