The purpose of this study is to confirm the psychological evaluation according to Mizukage's fluctuation period and viewing angle of Mizukage, and the effect on peacefulness according to changes in brain waves. In the first experiment, videos 1-6, evaluated as peaceful, and videos 1-2 evaluated as non-peaceful were extracted. Using these two videos in the second experiment, the psychological and physiological effects of peacefulness were investigated. It was found that a viewing angle of 5.7° × 9.2° had the most peacefulness for both videos 1-2 and 1-6. A narrow viewing angle has a large proportion of P3 and P4 α waves. Meanwhile, in viewing angle 9.2° × 5.7°, the ratio of the O2 θ wave was large. It was found that the viewing angle needs to be adjusted in order to obtain peacefulness with Mizukage because brain activity and subjective evaluation change depending on the viewing angle.