At the time of voltage adjustment, a selector (23) outputs data (D01, D1) externally received, to a current adjustment unit (24). The current adjustment unit (24) changes current (I01) in accordance with the data (D1) so that a voltage (VOUT) changes. The data (D1) obtained when the voltage (VOUT) is determined to be a certain value becomes data (D2) to be stored in a storage unit (22). At the time of a normal operation, the selector (23) provides the data (D2) output from the storage unit (22), to the current adjustment unit (24). Accordingly, even at the time of a normal operation, a power supply circuit (1) can output the voltage (VOUT) of high accuracy. It is therefore possible to provide a semiconductor device capable of outputting a voltage of high accuracy, and a power supply device provided with the semiconductor device.