PURPOSE: To rationalize the renewal time of parts by retrieving the information of the periodical renewal parts from the knowledge information and the renewal periods, etc., of plural information processors stored in a maintenance center system side.

CONSTITUTION: The first communication control means 21 of a maintenance diagnostic device 2 transmits the integrated value of working quantity and the identification name of the information processor 5 to the maintenance center system 1. There, in a renewal requesting means 12, the identification name same as the transmitted identification name is retrieved from an identification name storage part, and the position of the information related to the periodical renewal parts of the information processor 5 is retrieved from an individual information storage part from a corresponding pointer. Next, a working quantity difference calculating part calculates difference between the integrated value at the time of the last renewal and the transmitted working quantity about the first periodical renewal part among the information related to the information processor 5, and further, a renewal period retrieving part retrieves the name of the same kind as the kind of the periodical renewal part from a third storage means 15, and reads its renewal period. Then, only when the difference of the integrated value is over the renewal period, it outputs the identification name and the name of the kind to a parts request output means 11.