Provided is an interpolating A/D converter including a reference voltage generation circuit, an analog signal input circuit, a preamplifier group including a plurality of preamplifiers, and an interpolation circuit including a plurality of resistors. Reference voltages from the reference voltage generation circuit and an analog signal from the analog signal input circuit are input to the preamplifier group. The interpolation circuit outputs an interpolation signal by interpolating output signals of the preamplifier group. The preamplifiers amplify a differential voltage when a differential voltage between the analog signal and the reference voltages is smaller than a specified value, and the current flow of which is stopped when it is larger than the specified value. The plurality of resistors are connected in series between the adjacent amplifiers.