The present invention relates to novel compounds having histone deacetylase 6 (HDAC6) inhibitory activity, isomers thereof, or pharmaceutically acceptable salts thereof, the use thereof for the preparation of therapeutic medicaments, pharmaceutical compositions comprising the same, a method of treating disease using the composition, and methods for preparing the novel compounds. The novel compounds according to the present invention have histone deacetylase 6 (HDAC6) inhibitory activity, and are effective for the prevention or treatment of HDAC6-associated diseases, including cancer, inflammatory diseases, autoimmune diseases, neurological diseases and neurodegenerative disorders.