Recently the climate change issues due to the greenhouse effect have been discussed with respect to agricultural production. The likelihood of the impact on agricultural production of either extreme weather or climate change has been recognized, but the close examination for the causality between climate variables and rice yields has not been conducted. Thus the Granger causality test between climate variables and rice yields is carried out. We find that the rainfall, rainfall days, sunshine hours, and temperature significantly affect rice yields. Also, it is shown that the exceptionally low rice yields occurred in recent years can be explained by the related abnormal climates defined by meteorologists.