A host management system according to an embodiment includes: a data collecting device which collects real time data from a database of a subordinate supervisory control system; a history managing device which stores real time data which is collected through the data collecting device and stores and manages history data which accumulates the stored real time data; and a client associated device which is linked to a client device and transmits the real time data and the history data which are stored in the history managing device to the client device. The client associated device searches history data which the client device requests from the history managing device and transmits the searched history data to a client. [Reference numerals] (210) Data collecting device; (220) History managing device; (230) Client associated device
