The rotor of the turbine is monitored by sensors of the rotor vibrations arranged in at least one plane of measuring perpendicular to the axis of the rotor and by sensors of the absolute vibrations of the bearings. When using this method of processing, synchronically digitalized signals of the sensors of rotor vibrations, first the arithmetic mean of the individual harmonic bands in full spectrum in the frequency domain is calculated, by which means the information about the subharmonic components and their multiples in the full spectrum of these signals is transferred into the frequency band −1X to 1X, at the same time is by the calculation of the median estimated the level of the signal noise, with which individual frequency bands of the full spectrum are encumbered, and which is subtracted from the amplitudes in the individual frequency bands of full spectrum of the signals of the sensors.