The speed sensor is a new type of speed sensor that uses a magneto sensitive resistor as the sensing element. The core component uses a magnetic sensitive resistor as the detection element, and then undergoes a brand new signal processing circuit to reduce noise and improve functionality. Compared with the output waveforms of other types of gear speed sensors, the measured speed has minimal error and good consistency in linear characteristics. The sensing object is a magnetic material or a magnetic conductive material, such as magnetic steel, iron, and electrical steel. When a magnetic or magnetic material with protrusions (or indentations) on the object being measured rotates, the sensor outputs a pulse signal related to the rotation frequency to achieve the purpose of speed measurement or displacement detection.