There is provided an oxide sintered body including indium, tungsten and zinc, wherein the oxide sintered body includes a bixbite type crystal phase as a main component and has an apparent density of higher than 6.5 g/cm3 and equal to or lower than 7.1 g/cm3, a content rate of tungsten to a total of indium, tungsten and zinc is higher than 1.2 atomic % and lower than 30 atomic %, and a content rate of zinc to the total of indium, tungsten and zinc is higher than 1.2 atomic % and lower than 30 atomic %. There are also provided a sputtering target including this oxide sintered body, and a semiconductor device including an oxide semiconductor film formed by a sputtering method by using the sputtering target.