Hanshin Expressway Public Corporation (HEPC) is carrying out the daily inspection to detect damages in early stage on the service routes, approximately 220 km in length, in 1999. Moreover, HEPC has been carried out the regular inspection for all highway structures every 5 - 7 years to make an occurrence mechanism and a cause of damages clear. Then HEPC has judged the necessity of measures for repairing and strengthening based on these inspection results, and has made sure of the third person's safety. Thus, HEPC has maintained the highway structures healthy. However, there exists some structures in which it is impossible to make the causes of damage clear and to grasp the development of damages. So considering these structures as the monitoring structures, the field investigation (monitoring) has been carried out to make the causes of damage clear and grasping the development of damage basically. HEPC has made all of the field investigation results into database as structure's medical records of Kartell, and has made good use of the control and the management for Hanshin Expressway. This paper presents the results of monitoring for highway structures damaged by Alkali Aggregate Reaction (mainly Alkali Silica Reaction, hereafter called ASR).