This study conducted a multiple mediation analysis using sub-factors of basic psychological needs (BPNs) as mediators in the relationship between problem gambling and stress of gambling addicts to confirm that BPNs and stress, which affect gambling addiction, may be the result of problem gambling and to find effective intervention strategies. A total of 206 adults gambling addicts were screened by using CPGI. Descriptive statistics, correlation, hierarchical regression, and mediation analysis were conducted. Hierarchical regression analysis results yielded that problem gambling and sub-factors of BPNs were significant predictors of stress when controlling for gender and debt. The sub-factors of BPNs mediated the relationship between problem gambling and stress. These results indicated that BPNs and stress are not only the causes of gambling addiction but also the results from the harmful consequences of gambling addiction. The study supported the possibility of the psychological process of “Deficits of BPNs (of gambling users) → stress (of gambling users) → problem gambling → gambling addiction (of gambling addicts) → problem gambling → Deficits of BPNs (of gambling addicts) → stress (of gambling addicts)” among the variables and provided clinical implications for problem gambling counseling. Lastly, the limitations of this study and suggestions for further study were discussed.