It is important to analyze what kind of abnormal rainfall has been occurring in the Globe. This research shows the followings. Spatiotemporal distribution of abnormality of maximum daily rainfall is a little different than maximum rainfall with longer time durations. Increases in time series of global percentage of area of abnormal rainfall has relation with ENSO. However, we can not say that global averaged rainfall is increasing. In case of Mississippi floods in 1993, seasonal abnormality gradually increased from spring to summer, and then, suddenly decreased in autumn. This kind of seasonal abnormality may also occur only by shifting of timing of rainy season such as monsoon. This would be vital for even those who are familiar with every-year large floods such as in the area of Mekong Delta. Also, in this case, averaged rainfall over 2-degree mesh showed more abnormality than that point rainfall. This clearly implies that we must analyze abnormal rainfall considering spatiotemporal scales depending on size of target river basin.