A task management system includes: an attribute information acquiring unit acquiring attribute information indicating an attribute of a document corresponding to document data; a billing destination information generator extracting attribute information specifying a billing destination of a cost caused as a price of performance of a task using the document data from the attribute information acquired by the attribute information acquiring unit and generating billing destination information indicating the billing destination on the basis of the extracted attribute information; a process content information storage storing process content information indicating a content of a process performed on the document data by a task terminal used by a task performer; a task content specifier specifying the content of the task performed on the document data by the task performer on the basis of the process content information stored in the process content information storage; a cost correlation storage storing a correlation of the content of the task and the cost caused as the price of the performance of the task; a billing amount information generator generating billing amount information indicating a billing amount for the billing destination on the basis of the content of the task specified by the task content specifier and the correlation stored in the cost correlation storage; and a billing information storage correlating and storing the billing destination information generated by the billing destination information generator and the billing amount information generated by the billing amount information generator.