A message processing system with improved maintainability, while ensuring availability, is provided. A filtering section 131 determines a degree of importance of an error message transmitted from a monitoring target server 110 and performs a process of filtering. A queue 121 receives the error message after the process of filtering by the filtering section 131 and transmits the error message to all summarizing sections 132. The summarizing section 132 then performs a process of summarizing for summarizing error messages of the same type as to the error messages after the process of filtering by the filtering section 131. A topic 122 receives the error message after the process of summarizing from one summarizing section 132. The topic 122 then selects one mail transmitting section from mail transmitting sections 133 informing by e-mail transmission about the error message after the process of summarizing by the summarizing section 132, and transmits the error message to the selected mail transmitting section 133.