The purpose of this paper is to examine the part-time farming structure in Japan in relation to the expansion of the Agricultural Co-op (JA) Invested Farming company. The result of research in Chuzu town (Shiga Prefecture) shows that the structure is defined by different situations of employment between generations. Among those in the 60-years-and-older age group, males chose their vocation according to the size of their family farms. Males owning larger farms had no sustainable jobs except farming throughout their lives. Other males who owned average-sized or small farms tended to have sustainable jobs outside farming. In this case, however, the size of their farms had a strong connection to their salaries; farming was still necessary as a source of income. Females in this generation had no other jobs except farming. In this generation, farming was necessary to cover family spending. On the contrary, those in the 45-49 years age group have no need to maintain farming as a source of income, and all males have sustainable jobs outside of farming. Farm sizes have no relation to their salaries. Most females have jobs outside of farming. A couple's combined salary is enough to cover their family spending. When the older generation retires, part-time farming will vanish rapidly. Behind this trend, the lending of land is increasing and the number of farmers asking JA-invested farming companies for farm services is also increasing.