Provided are a dendrimer solid acid and a polymer electrolyte membrane using the same. The polymer electrolyte membrane includes a macromolecule of a dendrimer solid acid having ionically conductive terminal groups at the surface thereof and a minimum amount of ionically conductive terminal groups required for ionic conduction, thus suppressing swelling and allowing a uniform distribution of the dendrimer solid acid, thereby improving ionic conductivity. Since the number of ionically conductive terminal groups in the polymer electrolyte membrane is minimized and the polymer matrix in which swelling is suppressed is used, methanol crossover and difficulties of outflow due to a large volume may be reduced, and a macromolecule of the dendrimer solid acid having the ionically conductive terminal groups on the surface thereof is uniformly distributed. Accordingly, ionic conductivity is high and thus, the polymer electrolyte membrane shows good ionic conductivity even in non-humidified conditions.