A method of forming a contact structure with a contact spacer and a method of fabricating a semiconductor device using the same. In the method of forming a contact structure, an interlayer dielectric layer is formed on a semiconductor substrate. The interlayer dielectric layer is patterned, thereby forming a contact hole for exposing a predetermined region of the semiconductor substrate. A contact spacer is formed on a sidewall of the contact hole using a deposition method having an inclined deposition direction with respect to a main surface of the semiconductor substrate. The deposition direction may be set between the main surface and a normal with respect to the main surface. Further, there is provided a method of fabricating a semiconductor device using the method of forming the contact structure.