To analyze medical professors' evaluation of their online education experiences in an attempt to support faculty members and indicate the future direction of medical education. Faculty members who taught online in the first semester of 2020 at Yonsei University College of Medicine in South Korea were surveyed. The results of the survey were analyzed in June 2020. There were 88 respondents (35.1% of 251): 59 professors (67.0%), 16 associate professors (18.2%), and 13 assistant professors (14.8%). Their specialties lay in basic medicine (25.0%), clinical medicine (65.9%), and research and special purposes (9.1%). Sixteen participants (18.2%) had previous experience in online lectures; 23 (26.1%) reported that preparation time for online lectures was the same as before; 65 (73.9%) reported that the preparation time had increased; 38 (43.2%) faced difficulties in preparation and lecturing online, and among them 16 (42.1%) indicated inadequate interaction with students; 11 (28.9%) needed extra preparation time; and 11 (28.9%) attributed their difficulties to technical issues with the online platform. Participants' satisfaction with online lectures was low (p<0.001). In the free response question on overall experience with online education, 38.3% mentioned the need for an instructional design that allows students to actively participate and interact with professors, 29.5% mentioned the need for the establishment of an information & communications technology system, and 17.0% mentioned the necessity of faculty development. To prepare for the current pandemic and more in the long term, an appropriate educational support system must be constructed, and a learner-centered instructional design that enables wider interactions and active learning is needed.