A block polymer comprising: a hydrophobic block; and a hydrophilic block, wherein the hydrophilic block includes a unit derived from a compound represented by the following Chemical Formula 1, and the hydrophobic block includes a cationic group and a halogen group: 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)mPO 3 H - M + or -O(CF 2)mPO 3 2- 2M +; m is an integer of 2 to 6; M is a group 1 element; R 1 to R 5 are the same as or different from each other, and each independently hydrogen; a halogen group; or a hydroxyl group; at least two of R 1 to R 5 are a halogen group; or a hydroxyl group; R 6 and R 7 are the same as or different from each other, and each independently a halogen group; L 1 is a direct bond; -S-; -O-; -N -; -SO 2 -; or a substituted or unsubstituted alkylene group having 1 to 10 carbon atoms; a is an integer of 0 to 2, and when a is 2, structures in the parentheses are the same as or different from each other; R is hydrogen; or a substituted or unsubstituted alkyl group; and n is an integer of 2 to 10, and when n is 2 or greater, structures in the parentheses are the same as or different from each other. a hydrophobic block; and a hydrophilic block, wherein the hydrophilic block includes a unit derived from a compound represented by the following Chemical Formula 1, and the hydrophobic block includes a cationic group and a halogen group: 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)mPO 3 H - M + or -O(CF 2)mPO 3 2- 2M +; m is an integer of 2 to 6; M is a group 1 element; R 1 to R 5 are the same as or different from each other, and each independently hydrogen; a halogen group; or a hydroxyl group; at least two of R 1 to R 5 are a halogen group; or a hydroxyl group; R 6 and R 7 are the same as or different from each other, and each independently a halogen group; L 1 is a direct bond; -S-; -O-; -N -; -SO 2 -; or a substituted or unsubstituted alkylene group having 1 to 10 carbon atoms; a is an integer of 0 to 2, and when a is 2, structures in the parentheses are the same as or different from each other; R is hydrogen; or a substituted or unsubstituted alkyl group; and n is an integer of 2 to 10, and when n is 2 or greater, structures in the 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)mPO 3 H - M + or -O(CF 2)mPO 3 2- 2M +; m is an integer of 2 to 6; M is a group 1 element; R 1 to R 5 are the same as or different from each other, and each independently hydrogen; a halogen group; or a hydroxyl group; at least two of R 1 to R 5 are a halogen group; or a hydroxyl group; R 6 and R 7 are the same as or different from each other, and each independently a halogen group; L 1 is a direct bond; -S-; -O-; -N -; -SO 2 -; or a substituted or unsubstituted alkylene group having 1 to 10 carbon atoms; a is an integer of 0 to 2, and when a is 2, structures in the parentheses are the same as or different from each other; R is hydrogen; or a substituted or unsubstituted alkyl group; and n is an integer of 2 to 10, and when n is 2 or greater, structures in the parentheses are the same as or different from each other.