The principal aim of this study was to conduct basic experiments to examine countermeasures against barium sulfate aggregation caused by denture adhesive in gastric cancer screening test. Experiment 1 ; barium sulfate aggregation was reconstructed in petri dishes and the degree of reducing aggregation by seven types of commercial drink and tap water was assessed visually. The most effective one was tap water. Experiment 2 ; two types of aggregation (severe and mild aggregation) were reconstructed using gastric phantom BMU-1, tap water of 30-150ml was added and the degree of reducing aggregation was assessed with the images. In the case of severe aggregation, the most effective quantity of tap water was 120 ml and the next was 150 ml with the following of 90, 60 and 30 ml (P < 0.05). In the case of mild aggregation, the order of effective quantity was 90, 60, 120, 30 and 150 ml (P < 0.05). The results of this study suggested that tap water drinking of the subject was effective for the reduction of barium sulfate aggregation in gastric cancer screening and the most effective quantity of tap water was 120 ml in the case of severe aggregation and 90 ml in the case of mild aggregation.