e g first floor to provide for the circumstances at that time fig3 is a flow chart showing the determining procedure of the optimum stand by floor of the free cage if one free cage occurs as designated by e 3 in fig2 in step s1 the operation controller 3 inputs a detection signal representing the occurrence of the free cage e 3 to the stand by control means 4 and obtains the operating states of the elevator cages e 1 to e 3 at that time and information regarding the cage calling states of the respective halls up to that time from the hall controller 1 and the cage controller 2 and transmits the information to the stand by control means 4 in step s2 when the information input unit 5 in the stand by control means 4 confirms the occurrence of the free cage e 3 the evaluation item arithmetic unit 6 calculates the evaluation item for the state that the free cage e 3 is stood by at a certain floor at that time on the basis of the fuzzy rules in the fuzzy rule group 9 in step s3 there are as the evaluation items at that time i the positions.