Disclosed are novel indanone derivatives, pharmaceutically acceptable salts thereof or enantiomers, a preparation method thereof, and a pharmaceutical composition for the prevention or treatment of viral diseases, comprising the same as an active ingredient. The indanone derivatives have excellent inhibitory activity against picornaviruses including coxsackie-, entero-, echo-, Polio-, and rhinoviruses, as well as exhibiting low cytotoxicity, so that they can be useful as an active ingredient of a pharmaceutical composition for the prevention or treatment of viral diseases including poliomyelitis, paralysis, acute hemorrhagic conjunctivitis, viral meningitis, hand-foot-and-mouth disease, vesicular disease, hepatitis A, myositis, myocarditis, pancreatitis, diabetes, epidemic myalgia, encephalitis, cold, herpangina, foot-and-mouth disease, asthma, chronic obstructive pulmonary disease, pneumonia, sinusitis or otitis media.