The present invention relates to a magnetic sensor which can detect a weak magenetic field and improve the detection precision with an easy and convenient configuration. A magnetic sensor is provided with a magnetic body changing the direction of a magnetic field input to a magnetoresistance effect element in the vicinity of the magnetoresistance effect element in which the resistance value changes according to the direction of the input magnetic field, the magnetic body has at leas one projection portion in the direction almost parallel to direction in which the magnetic induction occurs in the magnetoresistance effect element. The direction in which the projection portion of the magnetic body projects is substantially parallel to the direction in which the magnetization of the magnetoresistance effect element is fixed.