Provided is an information processing system that identifies communication terminal identification information of a portable communication terminal used by a user when the user uses communication through an access point. An information processing system includes a communication terminal identification information storage unit that stores the communication terminal identification information of the portable communication terminal that performs communication using the wireless communication device, a person identifying information comparison processing unit that determines whether there is a same person using at least two or more pieces of person identifying information acquired in a person identifying information acquisition device in a certain wireless LAN communication spot where the wireless communication device exists, and a communication terminal identification information narrowing-down processing unit that performs, from the communication terminal identification information storage unit, processing for narrowing down the communication terminal identification information of the portable communication terminal of the user who performs communication using the wireless communication device, by extracting pieces of communication terminal identification information corresponding to the respective pieces of person identifying information from the communication terminal identification information storage unit, and identifying common communication terminal identification information, when existence of the same person is determined as a result of the determination.