A planar reconfigurable antenna including a substrate, a metal layer, a master antenna, an auxiliary antenna and a switch set is provided. The substrate has a first surface and a second surface. The metal layer is disposed on the first surface of the substrate and the upper edge of the metal layer is in a convex arc shape. The master antenna is disposed on the substrate and partially overlaps the metal layer on a vertical plane of projection. The auxiliary antenna is disposed on the substrate and is placed opposite to the master antenna. The switch set is also disposed on the substrate and changes a connection relation of a plurality of directional devices in the auxiliary antenna to switch scanning directions of main beams generated from the planar reconfigurable antenna.