The present invention relates to a facsimile gateway device capable of easily avoiding interruption of facsimile communication due to a delay in data transmission via the Internet, without changing a communication procedure. A main control unit of the gateway device receives facsimile image data from one facsimile machine via the Internet, and stores the image data into an image data memory area of a hard disk drive. When transmitting the image data to a destination facsimile machine via a public switched telephone network, the gateway device transmits a TCF signal, to which error data is appended, if image data of one page worth is not stored in the image data memory area. The TCF signal is a procedure signal for facsimile communication, and is a test data for training. The error data is, for example, all "1" data.