A landmark used to effectively determine the location of an autonomous vehicle, and a self-localization apparatus and method using the landmark are provided. In the self-localization method, first, first and second outer line information and shape information are extracted from a landmark image received from a camera. Next, a projective invariant is calculated from the shape information and stored in a hash table. Thereafter, the calculated projective invariant is compared with reference projective invariants for a plurality of landmarks stored in a predetermined data storage area in the form of a hash table, thereby determining which landmark corresponds to the landmark image. Then, information on the distance and orientation of the determined landmark with respect to the autonomous vehicle is analyzed in response to the first and second outer line information.