Liquid crystal aligning agent, liquid crystal alignment film, and liquid crystal display element

Provided are a liquid crystal aligning agent, a liquid crystal aligning film, and a liquid crystal display element for obtaining a liquid crystal aligning film for a photo-alignment method that does not generate bright spots even when a negative liquid crystal is used, and that obtains good afterimage characteristics. A liquid crystal aligning agent containing at least one polymer selected from the group consisting of a polyimide precursor having a structure represented by formula (1) in the main chain and an imidized polymer of the polyimide precursor (R1 and R2 are a single bond,-O-,-S-,-NR12-or the like, R12 is a hydrogen atom or the like, A is an alkylene group having 2-20 carbon atoms, X is an alkyl group having 2-20 carbon atoms, and X is an alkyl group having 2-20 carbon atoms. B1 and B2 have the same structure and are divalent organic groups selected from the following structures. ) (R4 represents an alkylene group having 1-5 carbon atoms, and R5 represents a hydrogen atom or the like. )--B1-R1-A-R2-B