An object of the present invention is to provide an apparatus for successive deposition used for manufacturing a semiconductor element including an oxide semiconductor in which impurities are not included. By using the deposition apparatus capable of successive deposition of the present invention that keeps its inside in high vacuum state, and thus allows films to be deposited without being exposed to the air, the entry of impurities such as hydrogen into the oxide semiconductor layer and the layer being in contact with the oxide semiconductor layer can be prevented; as a result, a semiconductor element including a high-purity oxide semiconductor layer in which hydrogen concentration is sufficiently reduced can be manufactured. In such a semiconductor element, off-state current is low, and a semiconductor device with low power consumption can be realized.