The AtoN is subsidiary navigation facilities for ship to navigate safely. AtoN includes signs of visual, sound, special and radio. Receltly as GNSS and AIS are developed rapidly, AtoN has been considered as a promising candidate technique for ensuring fairway safety of ship. However, present AtoN systems are not adopted to ship fully, but are adopted to ship partly, and total management systems are not installed. In this study, AtoN Monitoring system based on AIS is developed. It consists of AIS system and AIS viewer program. In the system AIS gathers data of AtoN and ship information and AIS viewer is a program that plots AIS data on ECDIS.