Yugaku Ohara, along with Sontoku Ninomiya, is known as a representative agriculturalist and thinker who rescued and reconstructed the ravaged rural areas at the end of the Edo period. This study, as part of the study of the Japanese mentality, analyzed Yugaku's thoughts and practical activities concretely and empirically. Yugaku's ideology was systematized as the science of the holiness of heaven and earth, and was called Seonghak. It was an independent idea that gave the Samurai morality to the peasants. Filial piety was emphasized for the perpetuity of Ie, and it was emphasized that the soul should be rectified according to one's intelligence and skill. Emphasizing the perpetuity of Ie(家), Yugaku placed great importance on the education of children and women, and created a unique educational method called gaeko (換子). In addition, Yugaku, who settled in the Kanto region (Bousou) after his long wandering life, tried to rationalize the lives of peasants and organize the community in a new form in a unique way called ‘SeigakuShihou’ based on his own Seonghak. In particular, he created a cooperative called Senjo Kabu Cooperative and provided innovative guidance in terms of living and agriculture. In addition to improving the productivity of the village, the emphasis was on thrift through crackdown on public morals, joint purchases, and joint labor. In terms of agriculture, major projects were promoted such as farmland consolidation, land exchange and division, distribution and relocation of housing, construction of a model pioneer village called Shukuuchi, preparation of year-round worksheets, mulching, and self-sufficient fertilizer. Even after his death, Yugaku was interpreted in various ways in connection with the state of affairs, and he is a rural leader who has had a great influence on the present day.