The present invention relates to a method of manufacturing a high tenacity yarn and a high tenacity yarn manufactured thereby. More particularly, the present invention relates to: a method of manufacturing a high tenacity yarn, the method including coating a yarn made of at least one of nylon and polyester to obtain a coated yarn, wherein the coating material contains 3 to 35 parts by weight of a reinforcing agent composed of a mineral material per 100 parts by weight of a coating liquid containing polyurethane; and a high tenacity yarn manufactured thereby. Therefore, it is possible to manufacture a yarn having high tenacity and improved processability by processing a nylon or polyester yarn having a relatively low tenacity as compared with a high modulus polyethylene (HMPE) yarn by use of a yarn coating technique, and further to reduce production cost.