This study aims to describe the understanding of the concept of beach abrasion material in elementary school students at SDN 2 Merauke. This research is a qualitative descriptive study conducted on grade IV elementary school students with 32 respondents. Data collection methods used are observation, interviews, and diagnostic tests. The research was conducted in October 2018 according to the schedule of school lecturers to make it easier to collect data obtained from supporting sources of this study. The data is then analysed descriptively through four stages: data collection, data reduction, data presentation and drawing conclusions. The results of this study indicate that students' understanding of the concept of beach abrasion material in elementary schools varies greatly. This shows that the ability of students to understand material about coastal abrasion of concepts that have been learned by students during the learning process. The average understanding of scientific concepts obtained by students is 24.6% while 55.0% are misconceptions and those who do not answer or repeat questions as reasons for answers are 20.4%. The dominant concepts that experience misconception are; (1) understanding the concept of changes in the appearance of the earth on land (60%), (2) understanding the concept of the types of changes caused by the appearance of the earth (50%), (3) understanding the concept of coastal abrasion caused by sea waves (57%) (4) Understand the concept of erosion on high land (65%), (5) understand the concept of how to prevent landslides on high land (50%).