Abstract: Especially designed to allow the wheelchairs in which disabled persons move to pass from a lower level to a higher level and vice-versa, although it is also valid for mothers, with trolleys whether of babies, shopping, etc. or for any other similar application; the stairs have steps which can move upward and/or downward to be positioned coplanarly and establish a platform, whereto the disabled person's wheelchair can directly access, allowing this by horizontal raising and/or lowering of this platform to pass from one floor level to another. For this purpose, it is provided that each step is supported by a scissor structure, associated to a mechanism, preferably formed by a motor and a spindle, making it possible to simultaneously raise and/or lower, and in controlled fashion, all the steps to form the platform of direct access of the disabled person's chair.