It is not possible to generalize about the severity of antisynthetase antibody syndrome. Anti-synthetase antibody syndrome is not serious if it can be controlled by early treatment, but if it is treated at a late stage or if it is accompanied by complications, it has a poor prognosis and is more serious. Anti-synthetase antibody syndrome is a disease that occurs due to the dysfunction of its own myositis-specific antibodies, also known as Jo-1 antibody syndrome, and the main symptoms include myositis, interstitial lung lesions, Raynaud’s phenomenon, mechanic’s hand, fever, and symmetrical polyarthritis. If antisynthetase antibody syndrome is detected and treated early, the prognosis is good and it is usually not considered serious, but it is prone to antibody-positive relapses, so long-term treatment and follow-up are usually required. If detected at an advanced stage of symptoms, or if interstitial lung disease is found, the situation is serious and prompt medical attention is recommended. Patients with antisynthetase antibody syndrome are advised to consult a rheumatologist promptly for early treatment.