Small and medium enterprises (SMEs), as the motive power of economic and social development, play an essential role in the development process of societies. Having a powerful economic flow, power to adapt with changing environmental conditions the possibility of high competitiveness and diversity and innovation are one of the most important features of these types of enterprises. However, a significant percentage of these SMEs encounter with some difficulties during their life-cycle, resulting in their failure and losing their opportunities. According to the literature, entrepreneurs’ deterring competencies are partly responsible for these failures. the current study seeks to identify entrepreneurs’ competencies which deter the sustainability of their businesses. This exploratory study has been done implementing qualitative narrative interviews with a sample of 10 entrepreneurs in Iranian food industries who were purposefully selected and participated in the study. The interviews had been continued till when the theoretical saturation has been granted. The research data were first collected through event-based interviews and a biographical study of entrepreneurs, and finally the findings were obtained by coding method. As a result, 7 deterring competencies of entrepreneurs which interfere with their businesses’ sustainability have been identified as following: self-conceit, wavering, analytical failure, misconduct, business skills failure, job dissatisfaction, and lack of experience.