This study investigated the increase of floor impact sound caused by ceiling air space in test building. Firstly, the change in floor impact sound with and without ceiling air-space was measured. Noise reduction effect of perforated ceiling systems and glass wool at ceiling area was also investigated. It was expected that perforated ceiling systems could reduce air-spring effect in ceiling space. As a result, ceiling air space caused increasement of floor heavy-weight impact sound about 2~4 dB. On the other hands, perforated ceiling with sound-absorbing materials system could reduced heavy-weight floor impact sound by 3 dB.