Two-dimensional semiconducting transition metal dichalcogenides (TMDCs) are recently emerged electronic systems with various novel properties, such as spin-valley locking, circular dichroism, valley Hall e ect, and Ising superconductivity. In this thesis, magneto transport study was performed to atomically thin molybdenum disul de (MoS2), a representative material among TMDCs, to reveal its electronic properties such as valley Zeeman e ect and electron-electron interactions. Introduction was given to two-dimensional materials like MoS2, including the crystal structure, electronic band structure, and basic transport properties. Focus was placed on the K valley conduction band minima of MoS2, where spin-orbital coupling plays an important role and there are anomalous Landau levels (LLs) due to the massive Dirac dispersion. To carry out the experiment, high-quality encapsulated bilayer MoS2 samples were fabricated. The fabrication procedures were described in detail. Electrical measurements using low-frequency lock-in technique at cryogenic temperatures and high magnetic elds were also introduced. Facilities like Raman spectroscopy were used to characterize the samples. From the electronic measurements, results were obtained and analyzed in two parts: Chapter 3 and Chapter 4. Chapter 3 focuses on the analysis of the quantum oscillations and the valley Zeeman e ect. Rich information about the charge carriers was extracted from the quantum oscillations, such as carrier density and e ective mass. The two-to-one degeneracy lifting was determined, attributed to the valley Zeeman splitting of the K valley electrons, which in turn, proofs the bilayer system to be layer-polarized. Chapter 4 focuses on the many-body e ects in the LL spectrum. Crossings between two sets of LLs were observed, as the gate voltage varied. A spin/valley-resolved LK formula was developed for MoS2 to analyze the strange behaviors, which revealed the valley-resolved oscillations and a quantum Hall ferromagnetic-to-ferrimagnetic transition. By mapping the Landau fan diagram, density-dependent valley susceptibility was determined, which was enhanced by electron-electron interaction. Anticrossings and the nearby enhanced resistance were found, related to the Ising quantum Hall ferromagnetism.