PURPOSE: A glass material manufacturing method using waste glass is provided to cost-effectively remove network-modifying oxide from waste glass. CONSTITUTION: A glass material manufacturing method includes the following steps: foreign materials are removed from waste glass and coarsely crushed(S1); the crushed coarse waste glass particles are melted until a temperature gradient exists between the surface and the center of the waste glass particles(S2); the molten waste glass particles are gradually cooled to coagulate network-modifying oxide on the surface of a glass lump(S3); the glass lump is dropped to separate the coagulated network-modifying oxide from the surface of the glass lump(S4); the separated network-modifying oxide is removed(S5); the glass lump is re-crushed to form glass materials(S6); and the glass lump dropping process is repeated. [Reference numerals] (AA) Start; (BB) End; (S1) Pulverizing step; (S2) Melting step; (S3) Precipitating step; (S4) Separating step; (S5) Removing step; (S6) Re-pulverizing step