The present technology pertains to a sensor, a driving method, and an electronic apparatus that are able to improve dynamic range and reduce noise during AD conversion. An AD converting unit has a comparator for comparing an electrical signal and a reference signal with a varying level, and uses the result of the comparator, obtained by comparing the electrical signal and the reference signal, tocarry out AD conversion of the electrical signal. An attenuating unit attenuates the electrical signal supplied to the comparator in response to the amplitude of the electrical signal. The present technology may be employed, for example, when carrying out AD conversion of electrical signals.