The invention provides an electrochromic display device having at least a pair of substrate electrodes and an electrolyte solution interposed between the pair of substrate electrodes. One substrate electrode of the pair of substrate electrodes has a porous structure on its surface. A monomolecular film formed of a first molecule that has a functional group that is capable of adsorbing to the porous structure is adsorbed to the porous structure via the functional group of the first molecule. A monomolecular film of a second molecule that has a functional group that is capable of chemically bonding to the first molecule is provided on the monomolecular film formed of the first molecule via a chemical bond between the functional group of the first molecule and the functional group of the second molecule. Further, at least one of the first molecule and the second molecule is an electrochromic dye.