PLATE GLASS BLANK AND MANUFACTURING METHOD OF THE SAME, AND MANUFACTURING METHOD OF COVER GLASS PLATE

PROBLEM TO BE SOLVED: To provide a manufacturing method of a cover glass plate, which allows easily manufacturing of a cover glass plate having high-precision surface shapes on its both sides, and to provide a plate glass blank suitable for the manufacturing method, and a manufacturing method of the plate glass blank.SOLUTION: In a drop step (A), a constant amount of molten glass 3 is dropped to a lower mold 1 having a concavity part 1a. In a press step (C), the molten glass 3 on the lower mold 1 is pressed with an upper mold 2 having a concavity part 2a for molding to fill the concavity part 2a of the upper mold 2 with the molten glass 3 for forming a first plane s1, and to fill the concavity part 1a of the lower mold 1 with the molten glass 3 to form a second plane S2 having concavity and convex parts. In processing steps from (D) to (G), surface-grinding or -polishing is performed to flatten the second plane S2 to produce a cover glass plate 8.