A block polymer comprising: a hydrophobic block; and a hydrophilic block, wherein the hydrophobic block comprises at least one cationic side chain, and the hydrophilic block comprises a unit derived from a compound represented by the following Chemical Formula 1: wherein, in Chemical Formula 1, A is -SO 3 H, -SO 3 - M + , -COOH, -COO - M + , -PO 3 H 2 , -PO 3 H - M + , -PO 3 2- 2M + , - O(CF 2 ) m SO 3 H, -O(CF 2 ) m SO 3 - M + , - O(CF 2 ) m COOH, -O(CF 2 ) m COO - M + , - O(CF 2 ) m PO 3 H 2 , -O(CF 2 ) m PO 3 H - M + or -O(CF 2 ) m PO 3 2- 2M + ; m is an integer of 2 to 6; M is a group 1 element; R1 to R5 are the same as or different from each other, and each independently hydrogen; a halogen group; or a hydroxyl group; at least two of R1 to R5 are a halogen group; or a hydroxyl group; R6 and R7 are the same as or different from each other, and each independently a halogen group; La is a direct bond; S; O; NRa; SO 2 ; or a substituted or unsubstituted alkylene group having 1 to 10 carbon atoms; Ra is hydrogen; or a substituted or unsubstituted alkyl group; and n is an integer of 2 to 10, and structures in the 2 to 10 parentheses are the same as or different from each other. a hydrophobic block; and a hydrophilic block, wherein the hydrophobic block comprises at least one cationic side chain, and the hydrophilic block comprises a unit derived from a compound represented by the following Chemical Formula 1: wherein, in Chemical Formula 1, A is -SO 3 H, -SO 3 - M + , -COOH, -COO - M + , -PO 3 H 2 , -PO 3 H - M + , -PO 3 2- 2M + , - O(CF 2 ) m SO 3 H, -O(CF 2 ) m SO 3 - M + , - O(CF 2 ) m COOH, -O(CF 2 ) m COO - M + , - O(CF 2 ) m PO 3 H 2 , -O(CF 2 ) m PO 3 H - M + or -O(CF 2 ) m PO 3 2- 2M + ; m is an integer of 2 to 6; M is a group 1 element; R1 to R5 are the same as or different from each other, and each independently hydrogen; a halogen group; or a hydroxyl group; at least two of R1 to R5 are a halogen group; or a hydroxyl group; R6 and R7 are the same as or different from each other, and each independently a halogen group; La is a direct bond; S; O; NRa; SO 2 ; or a substituted or unsubstituted alkylene group having 1 to 10 carbon atoms; Ra is hydrogen; or a substituted or unsubstituted alkyl group; and n is an integer of 2 to 10, and structures in the 2 to 10 parentheses are the same as or different from each other. A is -SO 3 H, -SO 3 - M + , -COOH, -COO - M + , -PO 3 H 2 , -PO 3 H - M + , -PO 3 2- 2M + , - O(CF 2 ) m SO 3 H, -O(CF 2 ) m SO 3 - M + , - O(CF 2 ) m COOH, -O(CF 2 ) m COO - M + , - O(CF 2 ) m PO 3 H 2 , -O(CF 2 ) m PO 3 H - M + or -O(CF 2 ) m PO 3 2- 2M + ; m is an integer of 2 to 6; M is a group 1 element; R1 to R5 are the same as or different from each other, and each independently hydrogen; a halogen group; or a hydroxyl group; at least two of R1 to R5 are a halogen group; or a hydroxyl group; R6 and R7 are the same as or different from each other, and each independently a halogen group; La is a direct bond; S; O; NRa; SO 2 ; or a substituted or unsubstituted alkylene group having 1 to 10 carbon atoms; Ra is hydrogen; or a substituted or unsubstituted alkyl group; and n is an integer of 2 to 10, and structures in the 2 to 10 parentheses are the same as or different from each other. <EOS>