This paper aims to construct a theoretical framework to explore a creative design process, which might be described as a “reflective conversation with situation” in D. A. Schön's term. For this purpose, 1) we introduce C. S. Peirce's semiotics into the study on design process, 2) examine how we apply it to design processes, 3) obtain the cases of design processes through a design experiment, and 4) analyze those cases using Peirce's semiotic model. Thereby, we propose that the design process as a “conversation with situation” can be understood as circulative chains of signs on Peirce's sign division.