Uncomfortable vertical vibration, which is caused by walking and traffic vibration occurs in long spans on lightweight floors and pedestrian decks. In order to suppress such vibrations, Tuned Mass Damper (TMD) is most commonly used. Usually strokes of TMD are limited by rigid stoppers in order to avoid collisions with control targets. In case of large earthquakes, the stroke of TMD increases, so that TMD collides with the stoppers. Therefore it does not exhibit enough vibration control performance. In order to solve this problem, this paper proposes a TMD with buffers. This TMD has buffers, which suppress the stroke of TMD. The buffers are installed beside the TMD, and gaps between buffers and the TMD are a few millimeters. Thus, in case of environment vibration, collisions with buffers do not occur, and the TMD retains as good vibration control performance as conventional one. In case of large earthquakes, the TMD collides with buffers, so that strokes of the TMD are suppressed and the vibration response of target structures is mitigated. In this paper, the selection of parameters of the TMD with buffers such as gaps and specification of buffers was conducted by simulation analysis. In addition, an experimental model of the TMD with buffers was made. Then vibration control performance is investigated by vibration experiment. As a result, it was confirmed that the TMD has a good performance of vibration control and stroke suppression.