Provided is an image forming system that is capable of displaying an accurate preview image in pull output. A document-data-receiving unit of a server receives document data from a terminal. A data-type-determining unit determines whether received document data is direct-output data or pull-output data. A document-data-retransmitting unit, when document data is determined to be direct-output data, transmits the document data as is to an image forming apparatus. A model-information-acquiring unit, when document data is determined to be pull-output data, acquires model information from the image forming apparatus. A preview-creating unit performs rasterization of the document data according to the model information, and creates preview data. A preview-transmitting unit transmits preview data that is created by the preview-creating unit to the image forming apparatus.