Changes in floor vibration characteristics were investigated before and after the installation of dry-construction-method walls, and several examples of significant reduction in floor vibration when a floor slab was subjected to heavy-weight impact were observed. In this study, how the physical phenomena in dry-construction-method walls affect floor slab vibrations were investigated by both actual measurements and analysis, and a method for analytically evaluating the effect was developed. Comparison of the floor vibration characteristics for different floor structures and conditions of the dry-construction-method wall using the evaluation method reveals the possibility of reducing floor vibrations related to heavy-weight floor impact sound.