The purpose of this research was to investigate the conceptions about ecosystem of the elementary students. To find out the change of conceptions by lesson about ecosystem and the difference of the conceptions between rural and urban students, a free-answer form of questionnaire consisted of 11 items was developed, and sent to 175 students from two elementary schools which were located in rural and urban area. Their responses were collected and analysed. The major results of the analysis are as follows. 1. The most of students has misconceptions about ecosystem before lesson, although part of students (16%) had correct conceptions. Especially, most of students had misconceptions about environmental elements of ecosystem and material behavior in ecosystem. 2. It was shown that preconceptions formed before lesson might be too firm so that large part of misconceptions and incomplete conceptions (about 60%) should not be changed to scientific conceptions even after lesson. 3. Although the students in rural area had Less misconceptions compared to those of urban area before lesson, there were no differences on the degree of formation of correct conceptions after lesson.