A circuit diagram supplying apparatus 10, for supplying a user with whole contents of an device system circuit diagram, then requests a server 30 for first-of-all transmission of part-connection-drawing overall circuit diagram data in which connection diagrams LSd are added to a part placement diagram included in the circuit diagram and having electrical component parts PSd arranged therein. Then, after displaying a part-connection-drawing overall circuit diagram based on the transmitted and received part-connection-drawing overall circuit diagram data, the circuit diagram supplying apparatus 10 requests the server 30 for sequential transmission of circuit-element-drawing divisional circuit diagram data (a)-(e).