In order to monitor a farmer's operation automatically, we propose a farm operation monitoring system with 'Field Servers' and a wearable device equipped with an RFID reader and motion sensors. In this system, we try to monitor farm operation by analyzing data from the sensors and detected RFID tags which are attached to various objects such as farming materials, facilities and machinery. This method can be applied to various situations without changing the traditional system. By constructing the proposed system based on the Field Server system, we are able to provide effective management, complex analysis and interactive support applications for farm operation. In order to evaluate this system, we conducted some experiments with a prototype wearable device. By analyzing the pattern of RFID tags, which are detected through the user's field work, this system recognizes farm operations with high accuracy. In order to evaluate the interactive support according to a particular farm's needs, we constructed an application to provide useful information in real-time and to control specific machines in a coordinated manner. The results of these experiments show the effectiveness of this system. The experiments suggest the need for future studies of the wearable device, recognition method and practical system.