To suppress the breaking in the transportation by applying a solution containing an organic high polymer compound and a silane coupling agent on an edge part of a plate glass and drying to reinforce the edge strength of the plate glass.

The coating solution having ≤100 cps viscosity is obtained by adding the silane coupling agent in a solution prepared by dissolving the organic high polymer compound such as polyisocyanate resin, silicone resin, polyester resin, acrylic resin or epoxy resin, if necessary ≥20 wt.% synthetic rubber into 60-80 wt.% solvent such as toluene, xylene, ethyl acetate or normal hexane. The coating solution is applied on the edge part of the plate glass so as to be 50-100 g/m2 in the solution state and dried. As a result, the resin is infiltrated into microcrack of the edge part of the plate glass to bury it to prevent the development of the microcrack and the edge part of the plate glass is reinforced.