Disclosed is a conjugated diene random copolymer having an alkoxysilane unit, which is prepared by subjecting a conjugated diene monomer, an aromatic vinyl monomer and an alkoxysilane monomer having a specific structure to emulsion polymerization, and in which the copolymer contains an alkoxysilane unit in the backbone thereof and is thus enhanced in the degree of dispersion and affinity to an inorganic reinforcing material such as carbon black or silica, and is useful as a rubber material for tires having superior mechanical and dynamic properties.