Disclosed is a highly transparent fiber-reinforced composite material including an assembly of cellulose fibers of 4 to 200 nm average fiber diameter impregnated with a matrix material so as to not only remedy the moisture absorbency attributed to cellulose fibers but also further improve transparency. There is provided a fiber-reinforced composite material including an assembly of cellulose fibers impregnated with a matrix material. In the fiber-reinforced composite material, hydroxyl groups of cellulose fibers are chemically modified through a reaction with one or more chemical modifiers selected from the group consisting of an acid, an alcohol, a halogenating reagent, an acid anhydride, and an isocyanate so that the ratio of a functional group introduced by the chemical modification is 5 to 40 percent by mole based on the hydroxyl groups of cellulose fibers before the chemical modification. The chemical modification of hydroxyl groups of cellulose fibers can reduce the hydrophilicity of cellulose fibers to thereby reduce the moisture absorbency of fiber-reinforced composite material. Further, the affinity between cellulose fibers and matrix material can be enhanced to thereby further improve transparency.