An apparatus for manufacturing a light guide plate is provided to apply a vacuum pressure into a molding space to lower an injection pressure within the molding space, thereby reducing the faults in an external appearance of the light guide plate. Mold resin is injected through a resin injection part(200). A light guide plate molding part(300) is connected to the resin injection part. The light guide plate molding part has a molding space(310) where a light guide plate is formed by using the mold resin. A vacuum pressure supplying part(400) is connected to the molding space of the light guide plate molding part. The vacuum pressure supplying part applies vacuum pressure into the molding space.
