1. An equipment diagnosis system for managing equipment, comprising: a deterioration model portion for modelling a deterioration state of a management target equipment and for outputting information of remaining life time of said management target equipment on basis of input information; stress information supply means for supplying said deterioration model portion with at least information on stress applied to said management target equipment; and simulation means which is supplied with remaining life time information from said deterioration model portion and for supplying said deterioration model portion with virtual stress information according to a selected plan, to perform simulation, whereby an operation state of said management target equipment is altered on basis of remaining life time information obtained by said simulation means.