Provided are a method for manufacturing a liquid crystal alignment film having high light utilization efficiency, a liquid crystal alignment film, and a liquid crystal display element. The liquid crystal aligning agent of the present invention is prepared by polymerizing polysiloxane and a monomer having liquid crystal properties, a photosensitive group, and a radical polymerizable group to obtain a polymer. After a side-chain-type polymer film (1) is obtained from the liquid crystal aligning agent, an aligning process is performed by irradiating polarized ultraviolet rays, then the product is heated, and side chains (2) of the side-chain-type polymer film (1) are realigned. A liquid crystal alignment film is then fabricated by heating the product at a higher temperature to fix the realigned state. The temperature of heating for realignment is 200 DEG C or lower, for example, or another temperature ranging from 10 DEG C higher than the lower limit of the temperature range at which the side-chain-type polymer film (1) exhibits liquid crystal properties to 10 DEG C lower than the upper limit of this temperature range. A liquid crystal display element is manufactured using the resultant liquid crystal alignment film.