Introduction: Dental fear is defined as the patient’s specific reaction towards stress related to dental treatment in which the stimulus is unknown. Aim of the study: To analyze the causative factor of fear during endodontic treatment. Materials and methods: A simple random sampling technique was used for the study and a sample size of 141 patients with an age group of 12-65 years, attending outpatient the Department of Operative Dentistry. The survey done was based on 5 questionnaires before and during endodontic treatment. Results: The percentage of the females was 55% while the males were 45% of the patients attending dental office, 57% of the patients were found not afraid of attending dental office, 62% of the patients were found afraid of seeing the anesthetic needle, 59% of the patients were feeling pain during removal of pulp, 55% of the patients were found not afraid of sensation of file introduced in the canal, and 57% of the patients experienced unpleasant taste of endodontic materials. Conclusion: The present study concluded that seeing the anesthetic needle, feeling pain during removing the pulp and experiencing the unpleasant taste of endodontic materials were the most causative factors respectively for the fear of endodontic treatment.