Life estimation of thermal print heads consisting of Ta2N thin-film resistors was investigated. Experiments on these thermal print heads included high temperature storage tests, pulse-heat tests, and actual thermal Printing tests under various conditions. From these experiments, four degradation modes, i.e., destruction, oxidation, crack formation, and abrasion modes, were identified. A flow chart was designed for the identification of the degradation modes. An Arrhenius plot was used to estimate the Ilfetime of the print head which degraded via the oxidation and/or the crack formation modes. In addition, a method to determine the head temperature while actually printing Was developed and degradation processes with aging were Observed.