The purpose of this study was to analyze the responses of pre-service elementary teachers to the plant learning using plant-observation activities and observation journal writings. Thirty pre-service teachers participated in this study. Before and after practicing plant observation and observation journal writing for 11 weeks, pre-service teachers' interest to plants, attitude to plant-observation teaching, and plant-observation teaching efficacy were examined using a questionnaire. Also, the observation journals, reflective journal writings, and interviews were analyzed to investigate their qualitative change. In addition, the pre-service teachers were classified by multi-dimensional scaling and cluster analysis with respect to attitude to plant-observation teaching and observation journal writing, and teaching efficacy. While the pre-service teachers showed significant increase of the interest to plants and plant-observation teaching efficacy, and positive change of the attitude to plant-observation teaching, there was a little difference between gender with more positive effects on females. The positive attitude changes of pre-service teachers included positive recognition about plants and the diversity, increased interest and curiosity about plants, careful observation about nearby plants, and independent learning and positive inquiry with plants. In terms of teaching efficacy, they showed positive change such as enjoyment and satisfaction with plant-observation, confidence as elementary teachers in the future, and recognition about the importance of elementary teachers for plant education. However, the changes were different among the groups classified by attitude to plant-observation teaching and observation journal writings, and plant-observation teaching efficacy.