Problem Based Learning (PBL) is one of methods which has been developed to promote student-centered learning and to pursue self-directed learning for life-long learning. The purpose of this study is exploring the possibility of Problem Based Learning (PBL) in college Earth science course. The participants of this study were fourteen students attending an Earth science class at Sookmyung Women's University in Seoul. PBL was implemented in the form of group project with utilizing Web-based course tool. We provided questionnaires and conducted interviews to figure out students' perception about PBL. The findings were as follows: Through a given experiences, (1) students participated more actively than LBL (Lecture Based Learning), (2) more students were engaged with self-directed learning, and (3) students made higher cognitive efforts. LBL seemed to be more efficient way to acquire factual knowledge. In the meanwhile, PBL did not seem to affect the improvement of communication skills. Students could not make use of Web-based course tool effectively in communicating with other team members. In this study, we found that college student participants preferred problems related to everyday life, environmental issues and interesting but unusual incidents. On the other hand, they felt difficult in open-ended problems, especially when they were asked to provide their own evaluation. On the basis of PBL experiment in this paper, we present one method of successful implementation of PBL and suggest topics which should be studied in the future.