the purpose of the present invention is to provide a copolymer allowing for an antifouling coating composition used for the formation of an environment - friendly antifouling coating film . the antifouling coating composition gives the coating film increased water resistance and can maintain the stable dissolution property and antifouling performance of the coating film without causing coating film defects such as a crack during long - term seawater treatment . an aspect of the present invention provides a copolymer for an antifouling coating composition , including a copolymer having , on a side chain , a group represented by chemical formula and having , on terminal , at least one of a group represented by chemical formula and a group represented by chemical formula .