Providing an alarm device for a clutch that issues an alarm the clutch lifetime prior to the clutch lifetime expiration, so that the information regarding the lifetime expiration is informed of; further, the failure protection measures for the clutch are adopted. An alarm device for a clutch, whereby a clutch disc connected to an input shaft is connected to or disconnected from a counter clutch disc connected to an output shaft, so that the input shaft is connected to or disconnected from the output shaft; wherein, the clutch comprises: the slip heat release threshold setting means 104, the slip heat release calculator 105, the alarm device 11; wherein, the slip heat release threshold setting means establishes a threshold criteria as to the clutch damage or the clutch lifetime, in a form of the relation between the heat release generated in a clutch slip operation (so called half-clutch operation) and the frequency of the heat release occurrences, thereby the heat release is measured per every predetermined time increment (interval), and the number of the occurrences is counted through the predetermined clutch slip operation duration under a clutch operation mode condition till the clutch is damaged, the duration being changed and repeated so that the frequency as to every predetermined heat release interval to which the generated heat release belongs is counted; the slip heat release calculator 105 calculates the heat release during the clutch operation, based on the hydraulic oil pressure in the actual clutch operation, as well as based on the relative circumferential speed between the disc and the counter disc; the alarm device 11 issues an alarm based on the calculation result through the slip heat release calculating means 105, as well as based on the slip heat release threshold setting means 104.