Abstract: An image data transfer method and system therefor transfer image data via network 10 connecting between a plurality of clients 100 and a server 400. A plurality of files are stored in image data base storage unit 430 and file search unit 420 searches the files to be processed by desired client from the image data base storage unit 430 in response to the search request of the client 100. The transfer protocol is sorted in transfer protocol storage unit 520 and transfer protocol management unit 150 transmits to a desired client via the network 10 the image data related to the file searched by the file search unit 420 specified the transfer protocol in the transfer protocol storage unit 520 based on the search request of the desired client.