To reinforce a concrete structure by applying an adhesive resin on a surface of the concrete structure such as a beam, a column, and a wall, and sticking thereto a reinforcing fiber sheet.

A bundle of aramid fibers are twill-woven to form a tape-shaped reinforcing fiber sheet having a width of 30 cm, and a surface 2a of a concrete structure 2 is primed with an adhesive resin 10, followed by sticking the thus formed reinforcing fiber sheet 1 to the primed surface. After sticking the sheet 1, an external surface of the sheet 1 is rolled by a roller so as to be pressed onto the surface 2a, and therefore air voids between the fibers of the sheet 1 are removed, whereby the applied adhesive resin 10 is infiltrated into the fibers. Then, the adhesive resin 10 is faced on the external surface of the sheet 1, which is then rolled by the roller, and after hardening of the adhesive resin 10, the entire sheet 1 is positively combined with the surface 2a in one body. Therefore, the concrete structure can be reinforced by the reinforcing sheet.