PURPOSE: To provide a serial parallel type A/D converter with a small area, low power consumption and high accuracy operated at a fast speed.

CONSTITUTION: Comparators 11-1n convert an analog input into digital data. An output current of a current source or current output type D/A converter 3 is varied with the digital data. An output voltage of a voltage source or voltage output type D/A converter 4 is varied with the digital data, An encoder 5 converts the digital data into a binary code or the like. A latch 6 stores the output of the encoder 5 in a prescribed timing. A digital over-range computing element 7 adds outputs of the encoder 5 and the latch 6 including an over- range area in a way of digital over-range. An output latch 8 outputs digital data to an external device in a prescribed timing. A sample-and-hold circuit 9 samples an analog input in a prescribed timing. A control circuit 9 controls the operation of the A/D converter.