Abstract: A compressor which is provided with a safety device so that it is possible to detect occurrence of a primary accident, for example, breakage of a connecting rod, in the early stage. The compressor has a pressure sensor installed at a predetermined position in the compressor to detect the level of pressure at that position, a memory means for storing the behavior of the pressure change at the predetermined position that is obtained when the compressor is running in a normal state, a means for judging the behavior of the pressure change actually taking place at the predetermined position on the basis of an output from the pressure sensor and making a comparison between the actual pressure change behavior and the pressure change behavior in the normal state that is stored in the memory means, and a means for suspending the compressor when the actual pressure change behavior is different from the pressure change behavior in the normal state.