A keyboard device includes at least one luminous key, at least one light-emitting element, a membrane switch circuit member, an opaque seal structure, and a transparent seal structure. The luminous key has a light-transmissible zone. The light-emitting element is electrically connected with the membrane switch circuit member, and disposed under the light-transmissible zone. A top surface of the light-emitting element is encapsulated by the transparent seal structure. The transparent seal structure is partially surrounded by the opaque seal structure. Consequently, the light beam from the light-emitting element is transmissible through the transparent seal structure, and directed to the light-transmissible zone.