Nagasaki Prefecture, located at the northwestern end of Kyushu, is more prone to localized heavy rainfall than other areas because it is strongly affected by rising sea surface temperatures in the East China Sea due to climate change. Therefore, we attempted to verify the “rate of change in heavy rainfall intensity”, which in necessary to consider flood control planning based on climate change, focusing on the Nagasaki Prefecture’s area. In addition to applying the rainfall data used in the study conducted by the Ministry of Land, Infrastructure, Transport and Tourism (Hereafter, the abbreviation "MLIT" will be used.), the study conditions were set based on the study conducted by the MLIT, taking into account the spatiotemporal scales of Nagasaki Prefecture. The results showed that the value for a 2°C rise in temperature was 1.16 times higher than the result of the MLIT’s study (1.14 times for the northwestern part of Kyushu reigon). On the other hand, the result for a 4°C rise in temperature was 1.32 times, which was slightly smaller than the result of the study conducted by the MLIT (1.36 times for the northwestern part of Kyushu region).