This study aims to identify the factors that influence adoption intentions towards portable Internet service, based on the individual characteristics that assist in creating markets and developing strategies. Two types of factors are defined: individual characteristics including demographics, existing services usages, prior knowledge, adoption attitudes, and service evaluations; and adoption intentions including the willingness to subscribe, subscription term, willingness to pay, usage type, and preferred terminal. The results indicate that the importance of demographic variables depends on adoption intentions, and that users of mobile Internet service and wireless LAN are probably targets for portable Internet service. Furthermore, the results demonstrate the need for an enhanced perception of the usefulness and ease of use of service, as well as an intensive marketing activity for potential users and a bearable innovation to stimulate the market for portable Internet service.