A rotation sensor includes a detecting portion, a rotational state determining portion and a pulse generating portion. The detecting portion detects a rotation of a rotational member and outputs a detection signal. The rotational state determining portion determines a rotational state of the rotational member on the basis of the detection signal in a predetermined period. The pulse generating portion generates and outputs a first pulse and a second pulse, of which waveforms differ from each other, in response to a rotational direction of the rotational member after the predetermined period. The pulse generating portion further generates and outputs a third pulse regardless of the rotational state of the rotational member in the predetermined period.