One of the pathophysiological features of irritable bowel syndrome（IBS）is the presence of psychological abnormalities, including attentional abnormality. In this case study, we investigated the effect of attention bias modification（ABM）in a patient with IBS. We hypothesized that the attentional abnormality in IBS would be normalized after ABM implementation, as indicated by electroencephalogram（EEG）. One patient with IBS took part in this study. Five ABM intervention sessions were provided over a 2month period. One session of ABM comprised 128 trials, resulting in a total of 640 trials across the intervention period. EEG were measured during the first and fifth sessions using the international 10-20 system for EEG. ABM intervention almost normalized EEG activities in a patient with IBS patient. Moreover, by ABM implementation, his anxiety was reduced. These results suggest that the implementation of ABM in patients with IBS may normalize brain function associated with attention.