The present invention provides a deformation detection sensor which combines a magnetic resin dispersing a magnetic filler in a resin with a magnetic sensor, of which stability of detection property is highly enhanced.The present invention thus provides a deformation detection sensor which comprises: a cushion pad which comprises a magnetic resin, in which a magnetic filler is contained, and a polymer foam in which the magnetic resin is included, and a magnetic sensor that detects a magnetic change caused by a deformation of the cushion pad, wherein the magnetic resin has an elastic modulus of 0.1 to 10 MPa, and a production thereof.