A message sorting systems includes: an extraction block configured to extract some of a plurality of posted messages on the basis of a rule with respect to message posting person, reply destination, or contents; and a sorting block configured to sort the extracted messages through a machine-learning sorting device. A message sorting method includes: extracting some of a plurality of posted messages on the basis of a rule with respect to message posting person, reply destination, or contents; and sorting the extracted messages through a machine-learning sorting device.