The present invention relates to a zirconium based alloy composite having an excellent creep resistance and, more particularly, to a zirconium based alloy composite finally heat-treated to have the degree of recrystallization in the range of 40˜70% in order to improve the creep resistance. The zirconium based alloy comprises 0.8˜1.8 wt. % niobium (Nb); 0.38˜0.50 wt. % tin (Sn); one or more elements selected from 0.1˜0.2 wt. % iron (Fe), 0.05˜0.15 wt. % copper (Cu), and 0.12 wt. % chromium (Cr); 0.10˜0.15 wt. % oxygen (O); 0.006˜0.010 wt. % carbon (C); 0.006˜0.010 wt. % silicon (Si); 0.0005˜0.0020 wt. % sulfur (S); and the balance zirconium (Zr). The zirconium alloy manufactured with the composition in accordance with the present invention has an excellent creep resistance compared to a conventional Zircaloy-4, and may effectively be used as a nuclear cladding tube, supporting lattice and inner structures of reactor core in the nuclear power plant utilizing light or heavy water reactor.