Objectives: This study sought to identify dental hygiene students’ adult attachment, interpersonal competence, self-respect, and sociable support, and to identify factors that affect interpersonal competence. Method: A self-administered survey was conducted on 180 students attending dental hygiene schools nationwide from 14 February to 30 May, 2023. Descriptive statistics, t-test, one-way ANOVAs, Pearson correlation coefficient, and stepwise multiple linear regression analys were used, as determined by the SPSS 26.0 program. Results: Dental hygiene students’ interpersonal competence measured 3.61 points, adult attachment measured 3.44 points, self-respect measured 3.44 points, and sociable support measured 4.00 points. In terms of general characteristics, significant differences were found in satisfaction with college life and club membership. Interpersonal competence was positively correlated with adult attachment, self-respect, and sociable support. The factor that had the greatest impact on interpersonal competence of dental hygiene students was sociable support, with an explanatory power of 37.3%. Conclusions: In order to improve the sociable support for dental hygiene students, a social activity support network within and outside of school is needed.