The present invention relates to an antiviral composition against viral hemorrhagic septicemia virus in fish, the composition containing quercetin as an active ingredient. The composition of the present invention, administered through peritoneal injection, oral administration, or water tank administration, makes possible the prevention or treatment of diseases caused by viral hemorrhagic septicemia virus in fish having a great effect on the mortality rate of cultured fish, thereby contributing greatly to the cost reduction in the fish aquaculture industry and an increase in the added value.
