The paper aims to identify main factors affecting customers' decision to use mobile banking in Viet Nam. The research team conducted a survey among people who have not yet used and have been using mobile banking at commercial bank branches in three regions: Northern, Middle and Southern of Viet Nam. Based on the theoretical framework from UTAUT2 model combined with Belief and Security Awareness, the authors propose a research model to identify factors affecting intention and behavior of using mobile banking, with 600 questionnaires. The result indicates that several factors were evaluated to be more important than others were. The research points out that “Facilitating condition” did not affect intention of using mobile banking, however “Security awareness” and “Trust” positively affect the customer intention. Moreover, “Security awareness”, “Hedonic motivation” and “Social Influence” are factors that have the strongest effects on intention to use mobile banking. In addition, the result also illustrates the relationship between “Culture” with “Benefit Expectancy”, “Effort Expectancy” and “Hedonic motivation”.