The present disclosure provides: a magnetoresistive element having a large magnetoresistance change ratio (MR ratio); and a magnetic sensor, a reproducing head and a magnetic recording and reproducing device. The magnetoresistive element comprises a magnetoresistive film including a pair of body centered cubic (bcc) crystal structure CoFe ferromagnetic layers with a (001) crystal orientation, the pair of layers separated by a non-magnetic layer of Cu with bcc crystal structure.