A polymer of an embodiment includes a repeating unit containing a bivalent group represented by the following formula (1). R is hydrogen, halogen, an alkyl group, an alkanoyl group, an aryl group, a heteroaryl group, or the like. X is oxygen, sulfur, selenium, or the like. Y and Z each is a bivalent group selected from a carbonyl group, a sulfinyl group, and a sulfonyl group. However, a case where Y and Z are both the carbonyl groups is excluded.