Many plans to construct very large offshore floating structures are proposed, such as floating cities, airports, and so on. In the first report, the authors studied the response of the flexible structures in directional waves. The main results show that the flexibility of the structures affect their responses due to structural deformation. However, these responses are mainly in wave frequency regions. The low frequency or steady responses sometimes become sgnificant and cause fatal accidents. This paper is about the experiments conducted to investigate the responses of large structures in wide frequency region. In the first report, the structures are moored by a single buoy of a TLP type. Therefore, the large and slow oscillations are observed which cause rotation around yaw axis and displacement in sway direction. These oscillations cause difficulty in using such offshore structures for any purpose. In these experiments, described in this paper, another buoy is added to the mooring system in order to reduce such motions. Both ends of the structure therefore are moored by two buoys. The main purpose of this paper is to measure the responses of the structures in an oblique condition relative to the wave direction. In the experiments, two setting angles, 0 and 22.5 degrees are used to obtain comparative results. The results show that in the oblique condition the level of some slow oscillations decreased while the interactions between motions increased especially in low frequency responses.