The invention provides a display module, a display device and a display device manufacturing method. The display module comprises a first substrate, a second substrate, an optical adhesive and shadingglue. The first substrate and the second substrate are in opposite arrangement; the optical adhesive is used for adhering a glass cover plate and the first substrate and comprises an optical adhesiveopening, the first substrate comprises a first substrate opening which includes the optical adhesive opening in a direction perpendicular to the display panel, and an area, exceeding the first substrate, of the optical adhesive is a first step area; the shading glue and the first step area are coincided in a direction perpendicular to the display panel and cover one side, close to the first substrate opening, of the first substrate. The first substrate opening is larger than the optical adhesive opening, so that a first step is formed; the first step is capable of blocking up the shading glueand beneficial for the shading glue to cover the lateral side, close to a porous area, of the first substrate, and accordingly light leakage of the first substrate is avoided.