To provide a structure of an easily cleanable lower frame structure capable of providing a barrier free condition in a double sliding Shoji, a single sliding Shoji, or the like suspending a hanging piece from a Shoji lower rail and fitted in sliding grooves of the lower frame upper face and making it hard to accumulate dust, scale, or water in the traveling part of a Shoji sash sheave and facilitating the cleaning of the lower frame.

The hanging pieces 51e, 61e of the lower rail of the outside Shoji and the inside Shoji of a double sliding Shoji provided at the outdoor opening of a building are suspended down, thin streaks of an outside Shoji slide groove 13a and an inside Shoji slide groove 13b are formed at the upper face of the lower frame formed at a substantially flat face, and the suspending pieces are respectively fitted. In the lower frame structure in which the hanging pieces are fitted, the traveling parts of the upper face of the lower frame where the sash sheaves povided in the outside Shoji and the inside Shoji lower rails travel are pseudo-rails 19a, 19b with curvedly and finely protruded sectional shapes.