A composition for injection molding by which a reactive injection molded article of good mechanical strength and electrical conductivity is prepared is provided.The disclosed is a composition for injection molding which includes carbon fibrous structures in a liquid curing resin composition, at a rate of 0.1-20% by weight based on the total weight of the composition, wherein the carbon fibrous structure comprises a three dimensional network of carbon fibers each having an outside diameter of 15-100 nm, wherein the carbon fibrous structure further comprises a granular part with which the carbon fibers are tied together in the state that the concerned carbon fibers are externally elongated therefrom, and wherein the granular part is produced in a growth process of the carbon fibers.