Many system administrators sometimes carry pagers or note PCs to monitor the system from remote. Although the pager is easy to carry, it onlyreceives short messages. The note PC enables the administrators to investigate the system in detail. It is, however, heavy and takes much time to establish communication. We developed a remote monitoring system using mobile phone (i-mode phone). The system composed of two sub systems: a passive monitoring system and an active monitoring system. The passive monitoring system monitors the system, and send alarms via email and voice when a particular value of the system matches a pre-defined condition. The active monitoring system allows the administrators to interact with the remote system using i-mode capability. It displays current status of the system with color diagram and text.