The present invention can realize bright white display, a high contrast black-white display and full color display with a simple structure of element members, and provide a display element exhibiting high durability and a method of forming a porous layer in the display element. Also disclosed is a display element comprising a porous layer and an electrolyte between a pair of facing electrodes, wherein the porous layer comprises particles bonded to each other by a metal or nonmetal oxide, the metal or nonmetal oxide deposited from a treatment solution comprising a deposition promoter and a complex comprising a metal or nonmetal ion and a ligand via reaction of the ligand with the deposition promoter.