This paper presents a tensile stress evaluation of mild steel plates by chaos of Barkhausen noise. The stress of magnetic materials affects magnetic domains, so the amount of the stress can be evaluated by Barkhausen noise. After the evaluations of Barkhausen noise by the original signals, spectrums and auto‐correlation functions are performed, the reconstructed attractors which is one of the typical treatment of the chaos are examined to use them for the stress evaluation of the mild steel. © 2003 American Institute of Physics