A vital sign processing device according to an embodiment of the present technology includes a pulse-wave sensor unit, an output unit, and a first filter unit. The pulse-wave sensor unit outputs a pulse-wave signal. The output unit outputs a heart-rate information item on the basis of the output pulse-wave signal. The first filter unit sets a first frequency band on the basis of the output heart-rate information item, and allows the set first frequency band of the pulse-wave signal to pass through the first filter unit.