The brand personality, which was limited to products and companies, has recently been applied to advertising media as its role got more important. The literature has reported that traditional TV and cable TV channels have identical brand personalities. In this context, the current study aims to explore the brand personality of the Internet portal services and to examine how the factors of brand personality could make roles in the effectiveness of advertising. The results shows that there were similar and different aspects of brand personalities among major domestic portal services. The most prevalent factors of brand personalities are ‘ability,’ ‘innovation,’ ‘trust,’ and ‘unpreparedness.’ The exploratory power of each factor varies by portal services. Although ‘ability’ is the strongest one across all brands, the second factor was ‘innovation’ in two brands but was ‘unpreparedness’ in the other. Only one brand had ‘trust’ as the significant factor of its brand personality. There were different exploratory powers among these factors in each brand by types of message strategy. Some managerial implications for integrating message strategies and brand personalities of the portal service are provided.