Disclosed are an apparatus and a method of updating a key frame of a mobile robot. An apparatus for updating a key frame of a mobile robot includes a key frame initializing unit which initializes seeds which constitute a key frame in a first position of the mobile robot and a key frame updating unit which projects seeds in the initialized key frame onto a first image photographed in the first position to obtain a coordinate according to each of the seeds and projects the seeds with the coordinates onto a second image photographed in a second position in accordance with movement of a mobile robot to update the seeds of the key frame as a projected result.