This paper describes the application of RFID (Radio Frequency Identification) technology to prevention of collision accidents with heavy equipment such as hydraulic excavators and cranes. Past disasters involving heavy equipment are evaluated to clarify the causes of accidents, and the functions of support systems for preventing collisions are defined. A system design is proposed with a working area obtained using RFID technology that is given a role from defined functions. A prototype has been developed using an active type RFID tag for the functions of a support system. RFID tag data were obtained from an actual construction site, and it is clarified that the prototype is applicable to estimation of working areas for the prevention of collision accidents.