Undoped and Mn doped ZnO films with different percentage of doping concentration (2%, 4%, 6% and 8%) were synthesized by sol gel method with an annealing temperature of 400°C. As to investigate the physical properties and microstructures, the samples are characterized using FESEM. The surface morphology images on the films showed many spherical shaped nanoparticles and separate uniformly. Meanwhile, the optical properties were characterized using UV-Vis where the transmittance and band gap value were affected by certain amount of Mn concentration. These films achieve tunable band gap characteristics by means of changing the dopant concentration. At lower concentration, 2% and 4% of Mn, the band gap is reducing compare to undoped ZnO. At higher doping for 6% and 8% of Mn, the bang gap suddenly increased.