We have studied the electronic properties of molybdenum diselenide(MoSe_2) in both bulk and monolayer(zigzag and armchair) forms using density function theory.The metallic nature of the zigzag MoSe_2(ZMoSe_2)nanoribbon and the semiconducting behavior of the armchair MoSe_2(AMoSe_2) nanoribbon have been explored using a band structure calculated using self-consistent calculations.We have also studied the variation in the bandgap in the presence of a small amount of strain(uniaxial,biaxial).The effect of tensile strain has been investigated and shifts in the conduction band and valance band have been observed with different amounts of applied strain. We have studied the electronic properties of molybdenum diselenide (MoSe_2) in both bulk and monolayer (zigzag and armchair) forms using density function theory. The metallic nature of the zigzag MoSe_2 (ZMoSe_2) nanoribbon and the semiconducting behavior of the armchair MoSe_2 (AMoSe_2) nanoribbon have been explored using a band structure calculated using self-consistent calculations. We have also studied the variation in the band gap in the small amount of strain (uniaxial, biaxial). The effect of tensile strain has been investigated and shifts in the conduction band and valance band have been observed with different amounts of applied strain.