Resonance is known as an important phenomenon where individual creative moments resonate with each other during co-creation. The purpose of this study is to capture this co-creative moment as a resonant cognitive status with biosignal indicators. The authors conducted an experiment in which pairs of participants work on concept generation from two nouns and measured their dynamic creative status both subjectively and objectively with biosignal indicators fEMG and EOG. This study will help to understand co-creative cognitive phenomena and to improve the co-creative design process.