Objectives: The purpose of the study was to investigate the related factors to dental fear in some adults. Methods: A self-reported questionnaire was filled out by 320 adults in Seoul and Gyeonggi-do from April to June, 2013. Except 14 incomplete answers, data were analyzed by SPSS 18.0 program. The questionnaire consisted of general characteristics of the subjects(7 questions), dental fear related factor(18 questions), distrust for dentist(15 questions), and distrust for dental hygienist(11 questions). The instrument for dental treatment fear was Dental fear Survey(DFS) adapted from Kleinknecht and partly modified by Choi. Out of 20 questions, 18 questions were reconstructed and score by Likert 5 scale. Higher score means higher dental fear. Cronbach alpha was 0.959 in the study. The distrust for dentist and dental hygienist was adapted from Choi and reconstructed and score by Likert 5 scale. Higher score means higher distrust for dentist and dental hygienist. Cronbach alpha was 0.937 in distrust for dentist and 0.874 in distrust for dental hygienist in the study. Results: Those who experienced dental pain tended to have dental fear. The reasons for dental fear were as follows; bad breath(2.96 out of 5 points, hereafter represented as of 2.96/5), dental caries(2.88/5), missing teeth(2.87/5) and tooth pain(2.77/5). The distrust for the dentist was the main dental fear in the adults. Conclusions: The dental fear was closely related to gender, experience of dental pain, oral symptoms and distrust for the dentist. As the psychological pain in the patients was mainly influenced by the trustful atmosphere, it is necessary to make the patient easy before treatment.