Since the research findings about ecological misconception of korean pupils have not represented until now, the primary purpose of this research was to identify high school students` misconceptions on ecology, At first, in order to find out high school students` misconceptions on ecology, a free-answer form of questionnaire, specially designed through analysis of high school biology curriculum, particularly ecological content, was developed and sent to ninety five high school students who had lived in Chungju area. Their responses were collected and analyzed qualitatively. As the results of the analysis of the data, the summary of this research are as follows. 1. High school students have remembered at the point of ecological terminology or simple knowledge than understood dynamic relations among ecosystem about ecology, These results were same with foreign pupils`. 2. They confused the output of plant respiration to oxygen. Especially, they recognized that invisible microorganisms, example far zoo plankton or fungi, didn`t do gas exchange. 3. Although many students usually misundertood that bacteria is toxic organism, they thought correctly the bacteria in ecosystem as decomposer was not toxic. 4. There were several misconceptions arose from biological terminology such as red blooming, red algae and winter migratory birds.