Countermeasures that can mitigate the global warming impact on rice production are needed. The large dehiscence of anther for pollen dispersal is one trait that shows tolerance of seed set to high temperatures under the global warming. The aim of this study is to determine the effect of long anther dehiscence on high temperature tolerance. Seven chromosome segment substitution lines and the seed parent with the different dehiscence lengths were subjected to high daytime temperatures. Elongation of dehiscence formed at the base of anther (BDL) by 100 µm mitigated the occurrence of high temperature induced sterility by 20% and improved tolerance to the high temperature by 0.66 °C. Relationship between the seed set and BDL was well explained by pollination, showing that quantitative information provided in the present experiment is reliable. The information is expected to be used in estimation of global warming impact and making countermeasures for it.