An X-ray CT apparatus has: a plurality of X-ray detection elements arranged in a matrix form; a QV amplifier unit having a plurality of QV amplifiers; a first connection unit connecting the plurality of X-ray detection elements and the QV amplifier unit; an AD converter unit having a plurality of AD converters; and a second connection unit connecting the QV amplifier unit and the AD converter unit. The plurality of X-ray detection elements and the QV amplifier unit are connected and the QV amplifier unit and the AD converter unit are connected so as to make different at least one of a signal processing characteristic of the QV amplifier unit and signal a processing characteristic of the AD converter unit for each X-ray detection element of the plurality of X-ray detection elements or for each of an adjacent plurality of X-ray detection elements.