This study aimed to analyze the effect of simultaneous and partial information technology and marketing strategy variables of the customer's decision and analyze the dominant variables influencing the customer's decision to use Bank Syariah Mandiri Mobile Banking. The research variables consist of customer's decision as dependent variable (Y), information technology (X1) and marketing strategies (X2) as the independent variable. This research is a case study using questionnaire. The questionnaire had previously tested the validity and reliability as a data collection instrument. Population is the m-banking customers at Bank Syariah Mandiri amounted to infinity (infinite population) because of that the sample size is determined based on the table Level of Confidence; 99% confidence level; sampling error of 15% amounted to 74 people. Then, the number of samples become 73 people because there is one respondents did not complete the questionnaire. Data was analyzed using multiple linear regression analysis and continued by testing of hypotheses F-test, t-test, and standarized beta. Results of the F-test showed there is significant positive effect simultaneously information technology and marketing strategy variable to the customer's decision. Significant positive effect also occurs partialy on information technology and marketing strategy of the customer's decision. Based on the results of t-test, information technology is a variable dominant influencing the customer's decision to use Mobile Banking. Bank Syariah Mandiri is advised to make the results of this study as an input in policy-making relating to Mobile Banking facility.