Provided is an information processing system which has a plurality of tags, a tag reader, a digital-pen, and a server. The plurality of tags each hold a tag identifier. The tag reader reads the tag identifier held in each of the plurality of tags. The digital-pen reads location information, which identifies a location where handwriting is made on paper. The server keeps work record including information that associates the tag identifier recorded in the server in advance with the location on paper. When it is judged that the read tag identifier and a handwriting location identified by the location information are associated with each other, the server judges whether or not the read tag identifier matches the tag identifier recorded in advance that is associated by the work record with the handwriting location identified by the location information. The server outputs a result of the judging.