PURPOSE: A producing method of a feed additive using sphagnum moss, and feed using the feed additive are provided to improve the nutrition of the feed using novel natural ingredients. CONSTITUTION: A producing method of a feed additive using sphagnum moss comprises the following: mixing 6-8 parts of potato starch by weight, 2-4 parts of boiled egg yolks by weight, 0.2-0.4 parts of sphagnum moss by weight, and 0.4-0.6 parts of water by weight; kneading the mixture, and firstly culturing the mixture at 20-25 deg C; inserting rice bran into the firstly cultured mixture, and secondly culturing the mixture at 20-25 deg C; and inserting the rice bran into the secondly cultured mixture, and thirdly cultured mixture at 20-25 deg C. The culturing processes are performed for 15-20 days.본 발명은 물이끼를 이용한 사료 첨가제 및 그로부터 제조되는 사료의 제조방법에 관한 것으로, 단백질 함량이 높고 향과 맛이 우수한 특징이 있다.