When a document, printing of which is designated, does not have a printable file format, an image forming apparatus determines whether a document management server which manages the document exists on the same network as that of the image forming apparatus. When it is determined that the document management server does not exist on the same network, the image forming apparatus acquires a file format printable by another image forming apparatus present on the same network, and transmits it to the document management server. The document management server receives the file format printable by the other image forming apparatus, and notifies the image forming apparatus of a list of an image forming apparatus or apparatuses capable of printing the document. Upon receiving the notification, the image forming apparatus instructs an image forming apparatus capable of printing the document about substitute printing. The instructed image forming apparatus substitute-prints the document.