Disclosed herein is mobile middleware, a context monitoring method, a context-aware system, and a context-aware service provision method, which support energy-efficient context monitoring. The mobile middleware receives a request for a CMQ from context-aware application programs, receives sensor data from sensors, monitors whether the CMQ is satisfied, and transmits an event to the context-aware application programs according to results of the monitoring. In this case, the mobile middleware controls the sensors so that only sensor data required to determine whether the CMQ is satisfied needs to be transmitted so as to reduce energy consumption during the performance of the monitoring. Therefore, the mobile middleware can perform energy-efficient context monitoring, required by the context-aware application programs.