The present invention provides a complex oxide sintered body 10 wherein Zr/(In + Zr + Y) is 0.05 to 4.5 at% and Y/(In + Zr + Y) is 0.005 to 0.5 at% in an atomic ratio when indium, zirconium, and yttrium are designated by In, Zr, and Y, respectively. Moreover, the present invention provides a sputtering target including the complex oxide sintered body 10 and a transparent conductive oxide film obtained by sputtering the sputtering target.