The purpose of this paper is to examine evidence for the existence of dark matter in the Milky Way by analyzing the rotation curve of the Milky Way. The data was collected from 21cm radio wave and was processed from raw data to plot of
rotation curve of the Milky Way. Data were compared to the Kepler model and the exponential disk model, which both predict the rotation velocity of galaxy; the data did not support either model. Instead, another model, the isotheral sphere model, was evaluated in order to incorporate the velocity of dark matter, a kind of invisible matter, which produced a better fit to the data.