Generic medicine (GM), which is an alternative drug product for branded medicine (BM), is used less in Japan than in other OECD countries. Therefore, we investigate why the medical consumers of Japan avoid the use of GMs even though the efficacy and safety of the medicines have already been proven. We theorize that effectiveness or risk of GMs are related to the consumer attitude toward GMs is affected by the behavioral approach/activation system (BAS) which promotes actions to reach the desired state, and the behavioral inhibition system (BIS) which suppresses behaviors to avoid negative outcomes. To see which of the BAS and BIS dimensions are related to GM usage, we surveyed 374 Japanese consumers and found that Quality, Efficacy, Safety, & Cost-effectiveness with the BAS, and Functional Risk, Financial Risk, Social Risk, Physical Risk, Psychological Risk, & Time Risk with the BIS had a significant effect on consumer attitude to GMs. These results are important in that they 1), confirm the role of BAS/BIS in attitudes to GMs, 2), provide guidelines when marketing GMs, 3), help governments promote the use of GMs as a cost-saving measure, and 4), guide future surveys regarding consumer attitudes to GMs.