A polymer comprising: a first unit represented by the following Formula 103; and a second unit represented by the following Formula 2: in Formulae 103 and 2, L2 to L6 are the same as or different from each other, and are each independently a direct bond; -O-; a substituted or unsubstituted alkylene group; a substituted or unsubstituted arylene group; a substituted or unsubstituted divalent amine group; or a substituted or unsubstituted heteroarylene group, b2 is an integer from 1 to 10, when b2 is 2 or more, two or more L6's are each the same as or different from each other, Ar1 to Ar3 are the same as or different from each other, and are each independently a substituted or unsubstituted alkyl group; a substituted or unsubstituted alkoxy group; a substituted or unsubstituted aryloxy group; a substituted or unsubstituted aryl group; or a substituted or unsubstituted heterocyclic group, R1 to R8 are the same as or different from each other, and are each independently hydrogen; deuterium; a halogen group; a hydroxyl group; a nitrile group; a substituted or unsubstituted alkyl group; a substituted or unsubstituted cycloalkyl group; a substituted or unsubstituted aryl group; or a substituted or unsubstituted heterocyclic group, r4 and r5 are each an integer from 1 to 3, when r4 and r5 are each 2 or more, two or more R4's and R5's are each the same as or different from each other, m1 is a mole fraction and 0 < m1 < 1, m2 is a mole fraction and 0 < m2 < 1, m1 + m2 ≤ 1, X is any one selected from the following structures, in the structures, L11 is a substituted or unsubstituted alkylene group; or a substituted or unsubstituted arylene group, R10 to R13 are the same as or different from each other, and are each independently hydrogen; or a substituted or unsubstituted alkyl group having 1 to 6 carbon atoms, and when X is b2 is an integer from 1 to 3, L101 is a direct bond; -O-; a substituted or unsubstituted alkylene group; a substituted or unsubstituted arylene group; a substituted or unsubstituted divalent amine group; or a substituted or unsubstituted heteroarylene group, b101 is an integer from 1 to 9, and when b101 is 2 or more, two or more L101's are each the same as or different from each other. a first unit represented by the following Formula 103; and a second unit represented by the following Formula 2: in Formulae 103 and 2, L2 to L6 are the same as or different from each other, and are each independently a direct bond; -O-; a substituted or unsubstituted alkylene group; a substituted or unsubstituted arylene group; a substituted or unsubstituted divalent amine group; or a substituted or unsubstituted heteroarylene group, b2 is an integer from 1 to 10, when b2 is 2 or more, two or more L6's are each the same as or different from each other, Ar1 to Ar3 are the same as or different from each other, and are each independently a substituted or unsubstituted alkyl group; a substituted or unsubstituted alkoxy group; a substituted or unsubstituted aryloxy group; a substituted or unsubstituted aryl group; or a substituted or unsubstituted heterocyclic group, R1 to R8 are the same as or different from each other, and are each independently hydrogen; deuterium; a halogen group; a hydroxyl group; a nitrile group; a substituted or unsubstituted alkyl group; a substituted or unsubstituted cycloalkyl group; a substituted or unsubstituted aryl group; or a substituted or unsubstituted heterocyclic group, r4 and r5 are each an integer from 1 to 3, when r4 and r5 are each 2 or more, two or more R4's and R5's are each the same as or different from each other, m1 is a mole fraction and 0 < m1 < 1, m2 is a mole fraction and 0 < m2 < 1, m1 + m2 ≤ 1, X is any one selected from the following structures, in the structures, L11 is a substituted or unsubstituted alkylene group; or a substituted or unsubstituted arylene group, R10 to R13 are the same as or different from each other, and are each independently hydrogen; or a substituted or unsubstituted alkyl group having 1 to 6 carbon atoms, and when X is b2 is an integer from 1 to 3, L101 is a direct bond; -O-; a substituted or unsubstituted alkylene group; a substituted or unsubstituted arylene group; a substituted or unsubstituted divalent amine group; or a substituted or unsubstituted heteroarylene group, b101 is an integer from 1 to 9, and when b101 is 2 or more, two or more L101's are each the same as or different from each other.