This paper is concerned with the development of a floating offshore wind turbine (FOWT) utilizing spar-type floating foundation. In order to design such a structure, it is essential to evaluate the dynamic response under extreme environmental conditions. In this study; therefore, a dynamic analysis tool has been developed. The dynamic analysis tool consists of a multibody dynamics solver (MSC.Adams), aerodynamic force evaluation library (NREL/AeroDyn), hydrodynamic force evaluation library (in-house program named SparDyn), and mooring force evaluation library (in-house program named Moorsys). In this paper, some details of the developed dynamic analysis tool are given. In order to validate the program, comparison with the experimental results, where the wind, current, and wave are applied simultaneously, has been made. In this paper, only parked conditions are considered. The comparison shows that the principal behavior of the floating offshore wind turbine with spar platform has been captured by the developed program. However, when vortex-induced motion (VIM) occurs, the current loads and cross-flow responses (sway and roll) are underestimated by the simulation since the simulation code does not account for the effect of VIM.