In a semiconductor device including a semiconductor layer made of an oxide semiconductor, occurrence of variance in the characteristics of TFTs is suppressed. In a manufacturing process of a semiconductor device (100) where a passivation film (17) is to be formed at an upper layer of a semiconductor layer (11) made of an oxide semiconductor, deposition conditions of the passivation film (17) are set such that the proportion of pure metal (the ratio of pure metal to all the components of the semiconductor layer (11)) at an interface of the semiconductor layer (11) to the passivation film (17) becomes higher than the proportion of pure metal in the bulk of the semiconductor layer (11).