The present technology relates to a circuit substrate, an image sensor, and an electronic apparatus that are capable of suppressing generation of noise in a conductor loop, which is caused due to a change in the conductor loop. A circuit substrate according to the present technology includes a circuit that is formed of a conductor and is capable of forming a conductor loop, at least a part of the dimensions of the conductor loop being variable; and a plurality of conductors that are each formed at a position where an induced electromotive force is generated in the conductor loop by a magnetic field and each have a structure that suppresses a change in the induced electromotive force generated by a change in dimensions of the conductor loop, the magnetic field being generated by the plurality of conductors. The present technology is applicable to, for example, an image sensor and an electronic apparatus.