This study aims to analyze the diffusion of social innovations in job assistance for disabled people and includes detailed case studies of 7 business models which are created by social entrepreneurs in this field. According to the typology based on J. Gregory Dees’ Scaling Theory (Dees et al. 2002 & 2004), 7 cases are divided into “Scaling Out” cases, “Scaling Deep” cases and the “Pre-Scaling Out” cases which are rather resemble to “Scaling Out” cases in business model than “Scaling Deep” cases. The results of interviews with social entrepreneurs of these 7 cases showed that business models created by social entrepreneurs of “Pre-Scaling Out” cases seem to be pre-mature especially on the management of business rather than the business model itself. Also, social entrepreneurs seem to face difficulties in adopting the most appropriate organizational form to incorporate their activities or business. This is one of the most basic institutional issues to be solved to facilitate diffusion of social innovation in this field.