To provide a rotation sensor capable of stable information transmission without depending on rotational speed of a rotator.

This rotation sensor 11 outputs pulses S1, S2 showing the rotational speed of the rotator 10. The rotation sensor 11 is equipped with a modulation circuit 15 for modulating a conveyance wave having a higher frequency than the frequencies of the pulses S1, S2 based on an information signal showing information other than the rotational speed of the rotator 10, and an adder 16 for overlapping the pulse S1 with the modulated conveyance wave (modulated wave Sm1) and outputting it to an output wire 17.