The telescope Array (TA) experiment, currently under construction in Utah, USA, is an array of surface detectors with air fluorescence telescopes to study the highest energy cosmic rays of energy beyond 10(20)eV. The TA surface detector array will consist of 576 plastic scintillation counters, on a square grid with 1.2 km spacing, covering the ground area of 760 km. Each surface detector is outfitted with two layers of scintillators of 3m(2) area, readout electronics, and wireless LAN communication system, which are powered by solar system. The test of an Engineering Array with 18 surface detectors is currently operating after being deployed in December 2004. Here we present the design and the progress of the surface detectors of TA, focusing on the status of the Engineering Array.