Hydraulic breakers, the attachment devices of the excavators, refer to a machine that converts back and forth motions of pistons into energies to break objects down finely. As the use of hydraulic breakers has been steadily increasing world-wide, consumers have become more interested in not just the quality of hydraulic breakers but their reliability. This study show functions and usages of several main parts on hydraulic breakers. In addition, based on the effect of action of hydraulic breakers, FMEA was performed to figure out the major causes and manifestations of malfunctioning. As above mentioned, we analyzed reliability of hydraulic breakers by models, and the data that had been used for the analyses were obtained from malfunctioning data in the field.