Based on an analytical framework, this paper classified farmer’s identity into two types: traditional identity that is oriented toward simple farm production and enlarged identity that is oriented toward viability of a new service activity. Second, by data envelopment analysis, the result of managerial efficiency simulation of a two-sector model, that is, the main milk production and the educational activity, revealed that those with the enlarged identity could realize higher managerial efficiency than those with the conventional identity. Thus, it was revealed that a farmer’s identity makes a difference in managerial efficiency. The efficiency level, however, was not high, which means that there is much room for improvement in farm resource management. Consequently, when policymakers try to design support measures to develop tourism-related farm diversification, the perspective of the support measures for capacity building should be widened to include identity issues, which helps farmers widen their identity that enable them to be more efficiently acceptable for tourism activity.