An internal voltage generator according to an embodiment generates a reference voltage used for detecting data stored in a semiconductor memory. A first AD converter is configured to convert an external voltage supplied to the semiconductor memory into a first digital value. A second AD converter is configured to convert a temperature characteristic voltage that changes depending on a temperature of the semiconductor memory into a second digital value. An adder is configured to receive a reference voltage trimming address that specifies the reference voltage, the first digital value, and the second digital value, and to output a third digital value obtained by performing a weighted addition of the reference voltage trimming address, the first digital value, and the second digital value. A driver is configured to output the reference voltage responding to the third digital value.