As attention paid to development of oil and gas in deep waters has increased, various kinds of concepts of compliant structures have been correspondingly proposed as the production platforms. Among them, the guyed tower and the taut moored platform (also called as the tension leg platform, hereafter abbreviated as TLP) are considered the most expectant at the present time. The first actual one of each type of these structures is planned to be installed a couple of years later. Authors have carried out several series of two dimensional wave exciting tests on small scale TLP models and have developed the analysis methods for the phenomena observed at the wave exciting tests. In this paper, three dimensional wave exciting tests were carried out by using a small scale model in regular waves with variable wave angle. The linear response analysis program in the frequency domain and the nonlinear response analysis program in the time domain were developed in the three dimensional case. Comparing the experimental results with the calculated ones, the characteristics of the three dimensional responses and the nonlinear phenomena are discussed.