As Mobile Internet users grow rapidly, Mobile Internet Companies will be in a fierce race to catch a new customer. In this situation, companies want to identify of what factors make peoples use Mobile Internet in order to develop the effective Mobile Internet services and to supply the higher service quality. However, prior researches on Mobile Internet focused on technical area such as higher data delivery, efficient compression of images, so they do not have given companies beneficial materials for making fascinating Mobile Internet service. To offer the service development materials, this research investigated important factors to use Mobile Internet from the viewpoint of customer. Moreover, the study was progressed how much these factors influenced Mobile Internet actual usage. After being surveyed service adopting model and significant factors in Marketing and in MIS(Management Information System), this study was suggested Mobile Internet Adopting Model reflected in Mobile Internet characteristics. To collect the effective data, Internet survey had been done for two weeks. The respondents were identified if they were real Mobile Internet users and how much they had used Mobile Internet for a month. The results were that important factors of Mobile Internet usage were Usefulness, Usability, System Quality and Instant Connectivity. Perceived Value of Mobile Internet influenced Mobile Internet Behavioral Intention significantly and Behavioral Intention had a significant effect on Mobile Intent usage by results. This paper concludes with discussion of these results and their implications for researcher and Mobile Internet company managers.