Kawasaki disease is a form of vasculitis, mainly in small and medium arteries of unknown origin, occurring frequently in childhood. It is the leading form of childhood-onset acquired heart disease in developed countries and leads to complications of coronary artery aneurysms in approximately 25% of cases if left untreated. Although more than half a century has passed since Professor Tomisaku Kawasaki's first report in 1957, the cause is not yet clear. Currently, intravenous immunoglobulin therapy has been established as the standard treatment for Kawasaki disease. Various treatment strategies are still being studied under the slogan, "Ending powerful inflammation in the acute phase as early as possible and minimizing the incidence of coronary artery lesions," as the goal of acute phase treatments for Kawasaki disease. Currently, in addition to immunoglobulin therapy, steroid therapy, therapy using infliximab, biological products, suppression of elastase secretion inside and outside the neutrophils, inactivated ulinastatin therapy and cyclosporine therapy, plasma exchange, etc. are performed. This chapter outlines the history and transition of the acute phase treatment for Kawasaki disease.