PURPOSE: To perform highly accurate diagnosis and to detect shifting vibration in the earily stage by detecting the frequency component in vibrating waveforms and variation in pressure on the side of a bearing.

CONSTITUTION: The vibration of a rotary body is detected by a shaft vibration meter 2, amplified by an amplifier 3, converted to a digital value by an A/D converter 4, and analyzed into a frequency spectrum signal by a Fourier analyzer 5. A comparator 6 has each preset level corresponding to each frequency spectrum outputted from the Fourier analyzer 5. The pressure generated at a rotor sliding surface is transmitted to a pressure converter 20 through pressure detecting holes 16W19, detedted by a pressure detector 9, amplified by an amplifier 10, and inputted to a comparator 11. The surface pressure of the bearing is computed here. When the result exceeds a specific threshold value, the bearing load is decreased, and the result is outputted as the correlation to the other phenomenon. A judging device 7 judges the decrease in the bearing load, and sends the output to a display 8.