Online gambling has been a highly profitable market. In 2005, it has been reporting $12 billion of revenue. However, Macao as a famous gambling city still focus on its land based casino gambling though it has faced a development bottleneck recently. If Macao doesn't recognize the world online gaming market and does not stay in touch with online gaming, it runs the risk of being left behind while others compete in this market. I suggest, therefore, online gambling as a supplement for Macao’s gambling industry. As Macao's online gambling market is still in its early stages, this study investigated the key factors determining people’s acceptance of online gambling. This study viewed online gambling as a combination of technology and social activity so a research model was built by using constructs established in the Technology Acceptance Model (TAM) and constructs such as subjective norm, trust and personal beliefs to explain users’ acceptance of online gambling. Then, a questionnaire survey is conducted and 212 valid returns were collected, Finally, multiple regression analysis is applied to test the relationships in the research model. Overall, the data shows that respondents’ subjective norm, attitudes towards online gambling, and perceived usefulness influenced their intentions to use online gambling significantly. And attitude is also found to be a mediator between perceived ease of use, perceived usefulness & belief and intentions. Additionally, trust and belief also influence intentions indirectly. This study finds that trust will increase certain aspects of the perceived usefulness such as online casinos’ credibility, and belief will influence attitudes positively.