A method of growing a germanium (Ge) epitaxial thin film having negative photoconductance characteristics and a photodiode using the same are provided. The method of growing the germanium (Ge) epitaxial thin film includes growing a germanium (Ge) thin film on a silicon substrate at a low temperature, raising the temperature to grow the germanium (Ge) thin film, and growing the germanium (Ge) thin film at a high temperature, wherein each stage of growth is performed using reduced pressure chemical vapor deposition (RPCVD). The three-stage growth method enables formation of a germanium (Ge) epitaxial thin film characterized by alleviated stress on a substrate, a lowered penetrating dislocation density, and reduced surface roughness.