Study on the martensitic transition of the iron-chromium alloy during thermal cycling was performed by acoustic emission method. It was observed that the acoustic emission during martensitic transition in this alloy was composed only of the burst type. The Ms temperature determined by the acoustic emission method was nearly $360\,^\circ\!C$. During various stages of transformation, the amplitudes of acoustic emission were investigated. Emissions of small amplitude were dominant in the stage of initiation, emissions of large amplitude were generated in the middle stage, and of small amplitude were dominantly generated again in the final stage. During thermal cycling, total count of acoustic emission had decreased due to a gradually decreasing completeness of the transformation because of the accumulation of stabilized austenite.