In this study, we propose research methods to explore the nature of earth science by applying the phenomenological approach and NOS-family resemblance approach based on literature review. The phenomenological approach exploring the nature of earth science is a method of collecting, analyzing and synthesizing multifaceted features of earth science from intuitive sensory phenomena without prejudice. As a way of exploring the nature of earth science from a phenomenological point of view, we propose the NOS-family resemblance approach to the NOS. This approach provides a comprehensive explanation of NOS by combining the characteristics shared by different areas of science with distinct differences. Applying this method to exploring the nature of earth science, we can identify both domain-general and domain-specific characteristics that make sub-areas of earth science a 'family.' For example, through the networking of features shared by such sub-areas as geology, atmospheric science, oceanography, astronomy, earth system science, etc., we can extract the family-resemblance characteristics that make these sub-areas a family called earth science. Through these approaches to the nature of earth science, the richness, complexity, and dynamic nature of earth science can be revealed as a whole. In addition, we will be able to grasp the change in the sub-areas that constitute the earth science, which in turn changes the nature of earth science, and to contribute to establishing the status and development system of earth science as a school subject.