Kawasaki disease (KD) is a vasculitis syndrome that frequently develops coronary artery lesions (CALs). In the treatment of KD, the utility of high-dose intravenous immuno-globulin (IVIG) therapy has already been clarified, and it has been established as the first-line treatment method. However, since approximately 10% of patients are refractory to this IVIG therapy and 2.6% of all patients have coronary sequelae, 500 children with KD still remain every year in Japan. In this disease, it is necessary to calm inflammation within 10 days of onset in order to suppress CALs caused by a large amount of persistent inflammatory cytokines. Indeed, the early suppression of inflammation is an effective means of suppressing the onset of CALs. Here, we describe the pathophysiology of Kawasaki disease and plasma exchange (PE), which is a therapeutic method that can calm the hyper-cytokine state of this disease. The treatment result of PE for IVIG-refractory Kawasaki disease is outstanding, and an extremely large effect can be expected if it can be started before the appearance of CALs. It seems that it should always be considered as one of the powerful additional treatments in the future.