Dismantling behavior of aluminum/carbon fiber-reinforced plastic (aluminum/CFRP) bonded assemblies using dismantlable adhesives was investigated. These adhesives contained expanded graphite (EG) to facilitate the dismantling process by inducing volume expansion during heating. Our objective was to identify the optimal additive conditions of EG, which would allow for easy dismantling while maintaining adequate adhesive strength in aluminum/CFRP bonded assemblies during regular operation. To achieve this, various experiments with adhesives containing EG of different flake sizes and volume fractions were conducted. The experimental results demonstrated that a moderate addition of fine-flake sized (140 μm) EG (5 vol%) tended to provide the desired combination of sufficient adhesive strength and ease of dismantling.