Until recent years, it is generally considered that Liu Zongyuan must have been underestimated by Song Dynasty's literati and officialdom. The reason is because he was a political prisoner in charge of taking part in Wang Shuwen (王叔文)'s party, and he approved Buddhism. By this reason, very few researchers have taken notice to the relation between Liu Zongyuan and the revival of classical prose style in Song Dyndsty. There is a significant difference in the prose style between Tang (唐) and Song Dynasty, because Song Dynasty's literati critically followed the prose style of Han Yu (韓愈) and Liu Zongyuan's. Here two facts are taken into consederation; firstly the place of Liu Zong yuan's prose style in Song Dynasty; secondly, the influence of Liu Zongyuan as a statesman to the literati and officialdom of Song Dynasty. Even though he seemed to be looked down by the Song Dynasty's literati, we cannot deny the fact that he had given a great impact on them. In fact, in the beginning of Song Dynasty, Liu Zongyuan was highly praised and regarded as a good model of prose style equivalent to Han Yu. We thought that this high valuation is partly because of the immaturity of Neo-Confucianism (道學) at that time, and Liu Zongyuan's works had not yet been completely circulating. It was Su Shi (蘇軾) who played a great role in the popularity of Liu Zongyuan's literature. He highly appraised Liu Zongyuan's literature (especially, his poetry) and treated it as a model in writing. His attitude gave great influence to other people, and Liu Zongyuan's literature stimulated the Song Dynasty's style of writing. The valuation standard of Liu Zongyuan as a statesman is complicated. At the beginning of Song Dynasty, several persons who had not taken critical attitude to Liu Zong Yuan yet were called as pioneers of Neo-Confucianism. As general, Liu Zongyuan was highly estimated. But after the period of Song Qi (宋祁)'s History of Tang Dynasty (『新唐書』) had been written, more criticisms about Liu Zongyuan were found. This seemed to have a close relation with the growth of Neo-Confucianism. By further study, it was found that they blamed Liu Zongyuan and at the same time they praised him on the same matter from different point of view. This is due to the fact that Song Dynasty's literati and officialdom had dualism in thinking. The dualism is composed of utilitarianism (功利思想) which is based on the promising spirit (有爲之精神), and of the Neo-Confucianism's ethics (名分思想). We thought that Liu Zongyuan's political belief and its spirit are the principle of Song Dynasty's utiliarianism.