The present invention provides a method for manufacturing a liquid crystal display device capable of suppressing display unevenness around a seal in the case of performing PS treatment on a horizontal alignment film formed from a photoactive material. The method for manufacturing a liquid crystal display device of the present invention includes the steps of: forming a horizontal alignment film containing a photoactive material on at least one substrate of a pair of substrates; dropping a liquid crystal composition containing a liquid crystal material and a monomer on one of the pair of substrates, the monomer being contained in an amount of 1.0% by weight or less in the whole liquid crystal composition; curing a sealing material applied to one substrate of the pair of substrates along an outer edge thereof by irradiating the sealing material with light whose wavelength is 40 nm or more longer than an absorption wavelength edge of the monomer; and forming a polymer layer that controls the alignment of liquid crystal molecules adjacent thereto on the horizontal alignment film by irradiating the liquid crystal composition sealed between the pair of substrates with light to polymerize the monomer.