Social anxiety is correlated with risk for easier dependence on marijuana use, and many works have been done to show marijuana use among college students is associated with mental health problems. Yet it remains unclear whether social anxiety serves as a predictor towards marijuana craving, which refers to an unrelenting desire and is often a criterion for the diagnosis of drug addiction. The present study examined the correlations between social anxiety, marijuana craving and marijuana use motives by analyzing data from questionnaires filled out by current Canadian undergraduates (N = 34). The data showed that higher social anxiety level was correlated with greater marijuana craving, and the frequently chosen motive to use marijuana was social conformity, which means becoming more consistent with other people’s behaviors, further suggesting that social anxiety played a role in leading desire for marijuana use. Identification of this association provides novel insights into the prediction and treatment for marijuana-related problems among college students and guidance for college policy design.