A semiconductor device includes at least one arm series circuit, a conductive first thermal buffer member, and a conductive second thermal buffer member. The arm series circuit includes an upper arm, a lower arm, a positive-electrode terminal, a negative-electrode terminal, and an output terminal. The first thermal buffer member has a linear expansion coefficient greater than a linear expansion coefficient of the first switching device and smaller than a linear expansion coefficient of one of the positive-electrode terminal and the output terminal. The second thermal buffer member has a linear expansion coefficient greater than a linear expansion coefficient of the second switching device and smaller than a linear expansion coefficient of one of the negative-electrode terminal and the output terminal.