This paper deals with the measured data obtained through the at-sea measurement of the TLP “EHIME”, an offshore nursery pilot firm station of Marino-Forum 21, of which tendons are parallel wire strands (PWS) protected by polyethylen sheath with specially manufactured cushion rubber rings at each ends and connected to a gravity type template through a belimouth shape structure. The measured data of the TLP dynamic responses are compared with theoretical estimation, and the strength performance of PWS as TLP tendons are discussed. The main results are as follows; 1) the TLP with the PWS mooring system has the same dynamic response characteristics as the conventional TLP with the steel pipe mooring system, 2) the mooring system by use of PWS type tendons adopted for the TLP “EHIME” exhibits sufficient strength and durability characteristics.