Sintered oxide body and sputtering target

Provided is a sintered oxide body for a high-quality and high-yield IGZO sputtering target that is most suitable for use in oxide semiconductor films, said sintered oxide body enabling the improvement of fluctuations in properties of an IGZO thin film and also enabling the improvement of the occurrence of cracking during the production of a target and during sputtering. A sintered oxide body which contains at least In, Ga and Zn, has a homologous crystal structure represented by the formula: InGaZnO 4 , and has a crystal grain diameter of 5 μm or less, a relative density of 95% or more and bend fracture strength of 100 MPa or more.