Production of cement had declined steadily throughout the Pacific War. The decrease had been slow at first and had quickened its pace since 1942. This study aims to explain the reasons why the cement industry declined during wartime even though Japan had enough raw materials, like limestone and clay. From this angle of study, the records based on questionnaire and interrogation conducted by the United States Strategic Bombing Survey just after the war were used to explain the discrepancies between the required production and the actual production. There are many possible causes for such decline of production, e.g. lack of skilled labor, fuel, transportation to consumers, and bomb damages to plants, etc. Throughout discussion, it is concluded that one of the most important factors of rapid decline of cement production was the failure of machinery which were irreplaceable during the war. Because most cement plants used imported machinery, replacement parts could not be imported after the war had begun, hence many plants had to close down until the end of the war.
