Symbolic Interactionism could be a useful theoretical basis for the sociological understanding about three themes derived from definitions of "architecture" and "architectural activity". The themes include 1)What is the meaning of social activity served by architecture, 2)What is the meaning of concretizing human being through symbolic forms and its relationship between human being and symbolic forms. and 3)How could architectural design be a process of self-understanding. The paper explores these themes in the topics of architectural sociology based on main concepts of Symbolic Interactionism. For this purpose, firstly, the paper outlines main concepts of the theory: symbol, objects, self & human behavior, secondly, discusses three topics related with these concepts in architectural sociology; 1)people, social behavior and material environment. 2)social space, space and social interaction, 3)architectural symbol, materiality and self. thirdly, summarize the sociological meaning of the definition of architecture and architectural activity, finally, the paper suggests the implication of Symbolic Interactionism to the architectural design thinking.