Background: The number of foreign-born patients with tuberculosis (TB) has been increasing in Japan, and the number of Vietnamese patients was the highest in 2019. Tuberculosis (TB) is the second leading cause of death from infectious diseases after coronavirus disease-2019 (COVID-19). As the prevalence of TB varies widely globally, measures must be tailored to local characteristics. The Directly Observed Treatment (DOTS) short-course was introduced by the World Health Organization as a global strategy to overcome these challenges. The purpose of this study is to develop an original risk assessment for treatment interruption for Vietnamese patients with TB to be used in Directly Observed Treatment (DOTS), a tuberculosis control measure. Methods: The researchers adopted the Delphi method. Public health nurses of mid-career or above (n = 15) who had conducted DOTS for several Vietnamese patients with TB were selected and surveyed about the content and surface validities of the draft risk assessment items for treatment interruption. The survey was conducted three times. The quantification of content validity and the review and modification of responses regarding each item were analyzed by the researchers. Results: The results identified the following risk categories: “physical characteristics”, “background of life during residence”, “treatment environment”, “understanding tuberculosis and disease acceptance”, and “cultural and value trends”. Conclusions: The results suggest the need to provide support for tuberculosis recovery from various perspectives, including the living environment of Vietnamese patients with TB, their social environment in Japan, and the culture and values of their country of birth and upbringing.