A contactless sensing device comprises a magnetic stripe fixed on a tested object, a detector and a processor. The magnetic stripe has arranged plurality of N-pole and S-pole blocks. The detector includes a fixed magnetic layer with fixed magnetic direction, a free magnetic layer with changeable magnetic direction influenced by external magnetic field, and an insulating layer separated the fixed magnetic layer from the free magnetic layer. While the object is moving to make the magnetic stripe pass through the detector, the magnetic direction of the free magnetic layer is influenced by the N-pole and S-pole blocks, such that the magnetic direction of the free magnetic layer is parallel or anti-parallel to the fixed magnetic layer. The induced change of the magnetoresistance further result in the obvious change of the output signal to the processor, and then the information of the object is sensed and calculated from the processor.