PURPOSE: To enable automatic detection of a trouble on operation noise due to the occurrence of blade bound phenomenon, by a method wherein, when the non-periodic degree of a period of operation noise of operation vibration of a rotary type compress- or exceeds a given value, an operation trouble signal is generated from a signal generating means.

CONSTITUTION: An operation sound signal from a rotary type compressor A, detected by a noise sensor 15 or a vibration sensor 16, becomes irregular in repetition of waveform in the case of a poor compressor to which blade 8 bound phenomenon occurs. Thereby, after a period of operation noise or operation vibration is calculated by a period calculating means 30, the degree of non-period (standard deviations) during period repeated the plural number of times is calculates. In the case of a poor compressor, the degree S of non-period exceeds a given value Smax, an operation trouble signal is generated from a signal generating means 32 and an operation trouble display lamp is lighten ON. This enables objectively quantitatively automatic detection of the occurrence of blade 8 bound phenomenon of the rotary type compressor A without relying on subjectivity which is heretofore usual.