Abstract: An object of the present invention is to transmit and receive a very large file with high reliability and with efficiency using the Internet, which is apt to be unstable, without special operation in a client PC. A file transmitting system according to the present invention is configured as a system in which a client PC 10 is connected via Internet 40 to a processing system comprising a WWW server 20, a management terminal server 30, an AP server 33, and a file server 34. Transmission of file data between a PC and a transfer file 36 of the file server is performed using HTTPS (HyperText Transfer Protocol Secure) that uses a dedicated program. The file data is divided into data having a fixed size, each of which is compressed for transmission. In addition, in preparation for occurrence of a failure, a checkpoint for retransmission is provided for each divided data. The dedicated program is devised so that multi-platform is supported.