Disclosed herein is a portable sunshade comprising a mast structure extending in a generally vertically direction, means for attaching the mast structure at its lower end to a support structure, a boom extending outwardly from the mast structure, having first and second ends, the first end being movably attached to the mast structure, a hub assembly attached to the second end of the boom, a plurality of elongated support ribs extending radially from the hub assembly, each of said support ribs, having one end rotatably attached to the hub assembly, a canopy positioned over the elongated support ribs and fastened thereto, the canopy having an opening in it corresponding to a predetermined position along the boom, and a boom support strut pivotably attached at one end to the upper end of the mast structure, and at the other end pivotably secured to boom at a predetermined position along the length of it, the boom support strut extending through the opening in the canopy at the point where it is connected to the boom.