Recently, two-dimensional transition metal dichalcogenides (2D TMDs) with layered structure have attracted much attention due to their unique electrical and optical properties. In particular, they exhibit a great potential for realizing the field effect transistors (FETs) which can apply for low power applications. Among them, molybdenum based 2D TMD (i.e., MoS₂) is one of the most studied compounds. However, FETs with multi-layered MoS₂ employed as a semiconductor layer must tackle many practical problems. For example, it has been speculated that either adsorbed molecules (e.g., water molecule) on the top of exposed MoS₂ channel layer or traps at the MoS₂-insulator interface causes the device instability such as the hysteresis generation in MoS₂ FETs. Until now, research on the hysteresis phenomenon of FETs with multi-layered MoS₂ has been focused on finding the origin of the hysteresis. However, the underlying mechanism(s) for this phenomenon has not yet been clearly clarified. Although recent several studies have suggested that the charge trapping and de-trapping processes at the MoS₂-insulator interface cause the device instabilities including hysteresis, it is not sufficient to explain the origin of traps giving rise to the hysteresis phenomenon of the MoS₂ FETs. In this work, we analyzed the hysteresis characteristics of the MoS₂ capacitors, using high frequency capacitance-voltage (C-V) measurements. Based on this analysis, we will demonstrate the roles of the interface traps originated from sulfur vacancy defects on the hysteresis generation in MoS₂ FETs. Based on these experimental results, we will propose a model to explain the hysteresis phenomenon observed in multi-layered MoS₂ FETs.