An image sensor, comprising: a plurality of pixels, each pixel including a photoelectric conversion unit that photoelectrically converts light and generates a charge, said image sensor including further analog/digital conversion units and a signal generation unit, wherein: one analog/digital conversion unit is provided for each pixel, wherein each analog/digital conversion unit comprises: a comparison unit that compares a signal due to the charge generated by the photoelectric conversion unit with a comparison signal (Vcom), wherein the comparison unit includes a first input unit, wherein the signal from the pixel is inputted to the first input unit, and a capacitor unit, wherein the capacitor unit includes a first capacitor provided in a first circuit layer, and a second capacitor provided in a second circuit layer laminated to the first circuit layer; wherein the signal generation unit is connected in common to the analog/digital conversion units and is configured to generate a reference signal (Vref) at a constant voltage and to supply said reference signal (Vref) to the analog/digital conversion units, wherein the capacitor unit is configured to generate the comparison signal (Vcom) on the basis of the reference signal (Vref) inputted from the signal generation unit via a signal line and to output said comparison signal (Vcom) to the comparison unit, wherein: a capacitance value of the first capacitor is smaller than a capacitance value of the second capacitor (72, 73), wherein: the first capacitor is disposed at a position closer to the comparison unit, than is the second capacitor (72, 73). a plurality of pixels, each pixel including a photoelectric conversion unit that photoelectrically converts light and generates a charge, said image sensor including further analog/digital conversion units and a signal generation unit, wherein: one analog/digital conversion unit is provided for each pixel, wherein each analog/digital conversion unit comprises: a comparison unit that compares a signal due to the charge generated by the photoelectric conversion unit with a comparison signal (Vcom), wherein the comparison unit includes a first input unit, wherein the signal from the pixel is inputted to the first input unit, and a capacitor unit, wherein the capacitor unit includes a first capacitor provided in a first circuit layer, and a second capacitor provided in a second circuit layer laminated to the first circuit layer; wherein the signal generation unit is connected in common to the analog/digital conversion units and is configured to generate a reference signal (Vref) at a constant voltage and to supply said reference signal (Vref) to the analog/digital conversion units, wherein the capacitor unit is configured to generate the comparison signal (Vcom) on the basis of the reference signal (Vref) inputted from the signal generation unit via a signal line and to output said comparison signal (Vcom) to the comparison unit, a comparison unit that compares a signal due to the charge generated by the photoelectric conversion unit with a comparison signal (Vcom), wherein the comparison unit includes a first input unit, wherein the signal from the pixel is inputted to the first input unit, and a capacitor unit, wherein the capacitor unit includes a first capacitor provided in a first circuit layer, and a second capacitor provided in a second circuit layer laminated to the first circuit layer; wherein the signal generation unit is connected in common to the analog/digital conversion units and is configured to generate a reference signal (Vref) at a constant voltage and to supply said reference signal (Vref) to the analog/digital conversion units, wherein the capacitor unit is configured to generate the comparison signal (Vcom) on the basis of the reference signal (Vref) inputted from the signal generation unit via a signal line and to output said comparison signal (Vcom) to the comparison unit,