A method of manufacturing a high tenacity yarn (A), the method comprising the steps of: a covering yarn being wound on a circumference of a core yarn ; wherein the core yarn comprises: a first core yarn part formed of a metal component; and a second core yarn part formed of a tungsten component, wherein a total thickness of the first core yarn part and the second core yarn part is formed to be 0.07 mm or less, and the covering yarn comprises: a first covering yarn part formed of a polyester yarn, a polypropylene yarn, or a nylon yarn having a thickness of 77.8 to 88.9 dtex (70 to 80 denier) and is wound on the core yarn in a clockwise or counterclockwise direction; and a second covering yarn part formed of a nylon yarn having a thickness of 211.1 to 244.4 dtex (190 to 220 denier) and being wound on an outer side of the first covering yarn part in a direction opposite to a wound direction of the first covering yarn part, wherein the second covering yarn part is heat-treated by passing through a heater that has a ring shape and is configured to radiate heat of 150 to 200°C, and then the second covering yarn part passes through a scratcher that has a ring shape and has scratching protrusions formed along an inner circumference of the scratcher, so scratches are formed on an outer circumferential surface of the second covering yarn part, and thus the second covering yarn part is softened. a covering yarn being wound on a circumference of a core yarn ; wherein the core yarn comprises: a first core yarn part formed of a metal component; and a second core yarn part formed of a tungsten component, wherein a total thickness of the first core yarn part and the second core yarn part is formed to be 0.07 mm or less, and a first core yarn part formed of a metal component; and a second core yarn part formed of a tungsten component, wherein a total thickness of the first core yarn part and the second core yarn part is formed to be 0.07 mm or less, and the covering yarn comprises: a first covering yarn part formed of a polyester yarn, a polypropylene yarn, or a nylon yarn having a thickness of 77.8 to 88.9 dtex (70 to 80 denier) and is wound on the core yarn in a clockwise or counterclockwise direction; and a second covering yarn part formed of a nylon yarn having a thickness of 211.1 to 244.4 dtex (190 to 220 denier) and being wound on an outer side of the first covering yarn part in a direction opposite to a wound direction of the first covering yarn part, wherein the second covering yarn part is heat-treated by passing through a heater that has a ring shape and is configured to radiate heat of 150 to 200°C, and then the second covering yarn part passes through a scratcher that has a ring shape and has scratching protrusions formed along an inner circumference of the scratcher, so scratches are formed on an outer circumferential surface of the second covering yarn part, and thus the second covering yarn part is softened. a first covering yarn part formed of a polyester yarn, a polypropylene yarn, or a nylon yarn having a thickness of 77.8 to 88.9 dtex (70 to 80 denier) and is wound on the core yarn in a clockwise or counterclockwise direction; and a second covering yarn part formed of a nylon yarn having a thickness of 211.1 to 244.4 dtex (190 to 220 denier) and being wound on an outer side of the first covering yarn part in a direction opposite to a wound direction of the first covering yarn part, wherein the second covering yarn part is heat-treated by passing through a heater that has a ring shape and is configured to radiate heat of 150 to 200°C, and then the second covering yarn part passes through a scratcher that has a ring shape and has scratching protrusions formed along an inner circumference of the scratcher, so scratches are formed on an outer circumferential surface of the second covering yarn part, and thus the second covering yarn part is softened. <EOS>