Two-dimensional (2-D) metal dichalcogenides like molybdenum disulfide (MoS 2 ) may provide a pathway to high-mobility channel materials that are needed for beyondcomplementary metal-oxide-semiconductor (CMOS) devices. Controlling the thickness of these materials at the atomic level will be a key factor in the future development of MoS 2 devices. In this study, we propose a layer-by-layer removal of MoS 2 using the atomic layer etching (ALET) that is composed of the cyclic processing of chlorine (Cl)-radical adsorption and argon (Ar) + ion-beam desorption. MoS 2 etching was not observed with only the Clradical adsorption or low-energy (< 20 eV) Ar + ion-beam desorption steps; however, the use of sequential etching that is composed of the Cl-radical adsorption step and a subsequent Ar + ion-beam desorption step resulted in the complete etching of one monolayer MoS 2 . Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and atomic force microscopy (AFM) indicated the removal of one monolayer MoS 2 with each ALET cycle; therefore, the number of MoS 2 layers could be precisely controlled by using this cyclical etch method. In addition, no noticeable damage or etch residue was observed on the exposed MoS 2 .