According to one embodiment, there is provided a semiconductor device including an input terminal, an output terminal, an oscillation circuit, an adjuster circuit, a driver circuit, and a detector circuit. The input terminal receives a first clock. The oscillation circuit generates an internal clock. The adjuster circuit corrects a duty ratio of a clock. The driver circuit receives the clock from the adjuster circuit and supplies a third clock to the output terminal. The detector circuit detects that a duty ratio of a clock according to the third clock deviates from a duty ratio of a second clock according to the internal clock. The adjuster circuit adjusts a correction amount in tune with the second clock, and corrects a duty ratio of the first clock with the adjusted correction amount according to a detection result of the detector circuit.