To provide a magnetic sensor and a noncontact switch which prevents magnetic noise from being easily applied to a huge magnetic resistance element for detection from the outside of the magnetic sensor, and of executing stable magnetism detection.

The huge magnetic resistance elements R1, R2, R3 and R4 are disposed in a cylinder part 12a equally circumferentially divided into an N pole and an S pole, so that magnetic flux Z (magnetic field) is always provided to the resistance elements R2 and R2 from the cylinder part 12a. When a magnetic body 14 is positioned at a permissible position, the magnetic flux Z (magnetic field) is provided to the resistance elements R1 and R4 from the cylinder part 12a. When the magnetic body 14 is positioned at a shielding position, by shielding the magnetic flux Z from the cylinder part 12a by a shielding pipe part 14a of the magnetic body 14, the magnetic flux Z (magnetic field) is prevented form being provided to the resistance elements R1 and R4.

COPYRIGHT: (C)2004,JPO&NCIPI