The present invention relates to a composition for manufacturing a back contact for a crystalline solar cell. The back contact material used for manufacturing a crystalline solar cell, a front contact and back contact of which are formed on the front side and rear side of a wafer, respectively, comprises a mixture composition consisting of an acrylate- or cellulose-based resin, aluminum powder, an inorganic binder, and an additive for increasing adhesion to a wafer, wherein the aluminum powder is a powder mixture containing aluminum powder, the size of which is 30-100 nm, and aluminum powder, the size of which is 2-10 [mu]m. The composition of the present invention uses said types of aluminum powder, the sizes of which are smaller than those disclosed in prior art, thereby reducing Rs-contact resistance and thus enabling a solar cell to have excellent photoelectric conversion efficiency.