The purpose of this study was to examine whether the collision avoidance judgement of seafarers is affected by each information sources, radar and visual. 22 seafarers who had onboard experience participated in the experiments using ship-handling simulator. Subjects were divided two groups, one group was conducted experiment for visual source, and another group was for radar source. This study investigated influence of each information source basis on results of their judgement, reasons why they made the decision, vessels which they paid attention to during experiments, and evaluations of their decision making by themselves. As a result, the judgements in both sources showed no differences. It was suggested that ships which the subjects paid attention to the decision making was different between each information source, even if the results of their decision were the same.