To completely repair defects in window glass such as a vehicle window by injecting and permeating a photosetting resin of low viscosity comprising a urethane acrylate resin or the like in the damaged part of a glass face, them applying a photosetting resin of different viscosity thereon and hardening the resin with light.

After a photosetting repairing agent (A) having <50 mPa.s viscosity is injected and permeated in the damaged part of a glass face, a photosetting repairing agent (B) having 30 to 1,000 mPa.s viscosity is applied thereon and hardened. The repairing agent (A) preferably has 30 mPa.s viscosity so that it can permeate well in cracks of a complicated form, the repairing agent (B) preferably has 40 to 300 mPa.s viscosity and is a topcoat material to finish the glass surface with smoothness and durability. The repairing agents A, B are prepared by compounding polymerizable unsatd. compds. such as an urethane acrylate resin and siloxane macromonomer in a 90/10 to 3/97 solid content weight ratio and further, incorporating a photopolymn. initiator. The polymn. degree of the urethane acrylate resin is preferably 500 to 2,000.