1. An apparatus for refining subject activity classification, comprising: an input buffer receiving and storing activity classification values of activity data of a subject, measured by a sensor attached to a body of the subject, and object response data of objects associated with the activity data of the subject and measured by at least one sensor mounted on the objects; a first refining module extracting a predetermined section of the activity classification values, stored in the input buffer, extracting a sudden significant activity data, which occurs in a time shorter than a minimum time necessary for carrying out an activity corresponding to an activity classification value in the predetermined section, and refining the extracted sudden significant activity data to be identical with activity classification values preceding and following the sudden significant activity data; and a second refining module, if the sudden significant activity data is absent in the predetermined section, extracting an unsuitable pattern, which is not suitable for a continuous activity pattern of the activity classification values in the predetermined section and refining the unsuitable pattern to be identical with the continuous activity pattern by considering an activation time of the sensor mounted on the objects associated with the activity data of the subject.