The peculiarities of the movement of the martensite interfaces were studied during the forward transformation on cooling and the reverse transformation on heating of NiTi alloy in situ in transmission electron microscope. It was found that the sequence of the martensite shrinking on heating was not opposite to the sequence of the martensite formation on previous cooling. The sequence of the martensite formation on the second cooling was not the same as during the first cooling. The dislocations did not act as the obstacle for the martensite formation and did not help for the martensite nucleation and growth.