A deposition technique for forming an oxynitride film is provided. A highly reliable semiconductor element is manufactured with the use of the oxynitride film. The oxynitride film is formed with the use of a sputtering target including an oxynitride containing indium, gallium, and zinc, which is obtained by sintering a mixture of at least one of indium nitride, gallium nitride, and zinc nitride as a raw material and at least one of indium oxide, gallium oxide, and zinc oxide in a nitrogen atmosphere. In this manner, the oxynitride film can contain nitrogen at a necessary concentration. The oxynitride film can be used for a gate, a source electrode, a drain electrode, or the like of a transistor.