The biological sensor includes a microcontroller that generates a driving signal, a light-emitting element that emits light in accordance with the driving signal, a light-receiving element that outputs a current detection signal based on an intensity of received light, and an amplifying circuit that converts the current detection signal into a voltage detection signal, amplifies an alternating current component of the voltage detection signal, and outputs an amplified detection signal. Furthermore, the microcontroller generates an offset signal that is applied to an offset circuit to offset the direct current component of the voltage detection signal and to obtain biological information by processing the amplified detection signal.
