The present invention provides a widely general-purpose A/D converting device. The A/D converting device comprises multiple signal conversion units each of which include: an A/D converter for converting an input analog signal into a digital signal with a predetermined number of bits; a D/A converter for converting the output from the A/D converter into an analog signal; a subtracter for subtracting the output signal from the D/A converter, from the input analog signal; and an amplifier for amplifying the output signal from the subtracter. The A/D converting device has a configuration wherein the signal conversion units are arrayed in multiple rows and columns. This allows the user to realize an A/D converting device having various types and levels of performance by making various combinations of the signal conversion units without change of the layout of the signal conversion units.