Today's art museums are transforming into viewer-centered complex cultural spaces where people communicate and experience, not just spaces for exhibiting and viewing. This expansion of the role of museum entails a change in the spatial structure of the museum. Therefore, we need a new interpretation standard and a flexible type classification system to explain a new type of art museum that emerges in the era of diversification. This study aims to derive a classification of types of art museums based on the concept of spatial structure that emphasizes individuality and connection between Raum Plan and Free Plan and to analyze changes of experiential aspects and modern trends according to the chronological flow of the museum's spatial structure. To this end, the Raum Plan and Free Plan, which are contrasting concepts, were discussed in conjunction with morphological and empirical features, divided into four areas and had different combination methods of "Raum form / Raum experience / Free form / Free experience", and a total of four types were derived: RR type, FF type, RF type, and multi-type to select and study cases for each type. As a result, in modern times, the types of 'spatial structure with free-plan experience in the form of Raum Plan (RF type)' and 'spatial structure that mixes Raum Plan and Free Plan (RR-FF multi-type)' are increasing, and these types of cases are creating an organic connection between 'people and works-architecture-city and nature' while providing various experiences to all visitors to the art museum. In other words, the morphological application of the Free Plan has gradually disappeared since the presentation of new concepts, but the experiential method has been highlighted and applied in modern art museums. Free Plan features, such as the separation and spread of gaze, random access, and network-shaped walk flows, allow visitors to experience their own space and provide different experiences in multiple visits, allowing individual visitors to revisit the museum. This type of classification and analysis attempt will help us understand the new spatial structural characteristics revealed in modern art museums, which were difficult to explain with the existing type classification.