The cushioning material having a sensor 1 includes a resin sheet 4 composed of photoelastic resin, a cushioning material 21 laminated on the resin sheet 4, a photosensor 15 including a light generating unit 5 and a light receiving unit 8 that are disposed to face each other so as to sandwich the resin sheet 4, and a processor 3 that detects a stress applied to the resin sheet 4 based on the light signal detected by the photosensor 15.