A semiconductor device (1) includes a non-volatile memory cell array (2), a write/read circuit (30) writing data into and reading data from the non-volatile memory cell array (2), a data input/output circuit (80), and a volatile memory cell array (40) including a first latch circuit (41) that is connected to the write/read circuit (30) and latches first data, and a second latch circuit (42) that is connected to the data input/output circuit (80) and latches second data. The device (1) may further include an inverter circuit (310) that inverts the first data in accordance with the number of bits to be actually written among the first data, and a control circuit (3) that causes the second data to be latched in the second latch circuit (42) while the first data is being written into the non-volatile memory cell array (2). This semiconductor device (1) has a shorter writing time and a smaller circuit area.