Device and method for detecting anomaly of an air conditioner, the method including the steps of (1) detecting an acoustic emission signal from a compressor in the air conditioner during operation of the air conditioner, (2) detecting parameters of particular components from the detected acoustic emission signal, and (3) comparing the detected parameters to respective references, to determine anomaly of the air conditioner on the whole, whereby permitting the most reliable detection of anomaly of the air conditioner.