In Japan, the Act on the Promotion of the use of Wood for Public Buildings etc. was enforced in 2010. As a result, the number of constructions using the timber structure became more popular for the buildings. However, the performance of the floor impact sound insulation in the timber construction buildings is often concerned as worse than the concrete constructions. In this paper, an experiment was carried out on a newly built wood-frame six stories building to investigate the performance of the floor impact sound insulation on five different floors; CLT panel floor, stressed skin panel floor, LVL, I-joist floor and chord truss floor. The result showed that the stressed skins panel floor has the highest performance. The paper also reports the floor vibration performances and sound insulation of separation wall in the timber construction building, and proposes an improvement plan for the better floor impact insulation performance in the timber construction buildings.