In this study, systematic errors and an error elimination method in digital image correlation are investigated for improving accuracy and spatial resolution of deformation measurements. Characteristics of the systematic error of measured displacements in DIC are investigated using an imaging process simulation. The speckle size of the random pattern on the target surface, the gap between each micro lens on the imaging sensor, and the relative position between the micro lenses and the imaged pattern on the micro lenses are considered in the simulation. The error investigation results show that those factors affect the characteristics of the systematic error. Possible error characteristics in actual DIC measurements using random patterns are considered. It is then found that the function of the possible error characteristics shows complex profile and the error becomes zero at integer displacements in pixel. In practical deformation measurement in DIC, the error profile can be obtained using additional measured shift data, if the actual shift amount as the relative translation amount of the target and the camera is known. The function approximation of the error profile and an error elimination method are investigated.