From the safety point of view, there are require to minimize risk for fire. Then market ask to use plastic materials which has frame retardancy to transportation, construction and Electronics & Electric. Rubber and elastomer material for those market are also require to achieve standard of frame retardant. Diethyl phosphate is effective halogen free frame retardant for engineering plastics, because it has higher thermal stability than common P-base frame retardant and lower risk for health in fire case. We evaluate it about effect to thermoplastic polyester elastomer which is one of the alternative material of PVC for cable material to reduce risk.