For the application to the window layer of $Cu(In,Ga)Se_2$(CIGS) solar cell, zinc oxide(ZnO) thin film was deposited at various temperatures by in-line pulsed DC sputtering. From the structural, optical, and electrical investigation and analysis, it was possible to obtain the lower thickness, the lower resistivity, and the higher transmittance at a higher process temperature. The energy band gap of ZnO was calculated using the transmittance data and was analyzed in terms of the dependency on temperature. From the X-ray diffraction(XRD) results, it was possible to conclude that a dominant peak was found about $34.2{sim}34.6^{circ}$(111) and crystallinity was obtained at a temperature above $150^{circ}C$.