To provide a method of reinforcing a cement structure enhancing a riveting effect on the cement structure, and a method of forming a delineator wall in a tunnel using the method.

The surface of the cement structure formed of concrete and/or mortar is coated with a two-liquid unsaturated polyester-based resin, and the unsaturated polyester-based resin permeates the interior of the cement structure to enhance waterproofness while reinforcing the surface of the cement structure. In the method of forming the delineator wall in the tunnel using the method of reinforcing the cement structure, the surface of an inside wall 11 of the driveway tunnel 10 to which the cement structure is adapted, is coated with the two-liquid unsaturated polyester-based resin with a white pigment and first beads of 25-200 μm in diameter added.