The nucleus accumbens (NAc) receives the dopaminergic projection from the ventral tegmental area and plays critical roles in the reward processing. Bupropion, an antidepressant and smoking-cessation aid, has a variety of pharmacological actions, including dopamine and norepinephrine reuptake inhibitions and nicotinic acetylcholine receptor antagonism. Although bupropion reportedly improves some cognitive functions, little is known about the effect on reward. Here we examined effects of the bupropion on the reward function by using monetary incentive delay (MID) task combined with functional magnetic resonance imaging (fMRI), which could elicit robust activation of the blood oxygen level-dependent (BOLD) signal in the NAc in association with increase in dopamine release during the gain anticipation. Fifteen healthy adults participated in a single-blind, placebo-controlled cross over study. They took orally either bupropion (150 mg) or a placebo and were subjected to the fMRI experiment.The NAc was activated during the gain anticipation in the placebo treatment. The bilateral NAc activations during the gain anticipation were more prominent in the bupropion than the placebo treatment. The percent signal change in BOLD activity was significantly increased in the bilateral NAc during the gain anticipation in the bupropion compared to the placebo treatment.These findings suggest that bupropion augments the reward function partly mediated by the increase in dopamine in NAc.