A pulse wave sensor includes a light sensor unit arranged to irradiate a living body with light from a light emitting unit and to detect reflected light or transmitted light from the living body by a light receiving unit, so as to generate a current signal corresponding to received light intensity, a pulse drive unit arranged to turn on and off the light emitting unit at a predetermined frame frequency and duty, a transimpedance amplifier arranged to convert the current signal into a voltage signal, and a mounting determination unit arranged to perform mounting determination by comparing an OFF voltage signal obtained by the transimpedance amplifier during an OFF period of the light emitting unit with a predetermined first threshold voltage.
