To provide a dialysis-treating apparatus monitoring system capable of communicating with an extrahospital terminal via the Internet without affecting an intrahospital network.

In a hospital equipped with a dialysis-treating apparatus monitoring system 1 monitoring a plurality of dialysis-treating apparatuses, a dialysate supply device 21 and a bulk powder dissolution device 22 execute dialysis preparation processing wherein washing and sterilization inside the devices are performed, during a period wherein a staff is absent inside the hospital, and stop the dialysis preparation processing when an error occurs during the dialysis preparation processing execution. On the other hand, when an error occurs in any dialysis-treating apparatus, a network camera selectively images a display of the dialysis-treating apparatus wherein the error has occurred of error-displaying displays 21D, 22D, 23D each provided in each dialysis-treating apparatus, and transmits image data indicating an image of the imaged display to a communication terminal 2 on the Internet via a mobile router 13 dedicated to the dialysis-treating apparatus monitoring system 1.