Abstract: A support structure for engaging opening and closing units to a track, wherein a support structure 1 comprises a support main body which is secured to each of a plurality of opening/closing units that move along an opening/closing section A of a predetermined length and a storing section B in contiguous with the section A, and which has oblique slidable contact sides each formed in parallel with each other at both ends of a horizontal plane thereof, side engagement members each formed in parallel along the side of each of the support main bodies for slidably engaging a plurality of adjacent support main bodies to each other when the main bodies are arranged in parallel with each other, a pulling engagement member integrally secured along one of the oblique slidable contact sides of the support main body and formed with an engaging groove and another pulling engagement member integrally secured to the other of the oblique slidable contact sides of the support main body at a position inside the blunt apex so as