1. A face identification device comprising: a storage unit for storing a plurality of feature values previously obtained for respective partial areas from a face image of a registrant; a processor comprising: a face detection unit for detecting a face of a person from an input image; a partial area designating unit for designating a plurality of partial areas of an area including the face, the partial areas corresponding to feature points of a detected face including at least one of an eye and a nose; a state determination unit for determining from the detected face whether an unfavorable condition for identification of the detected face has occurred and, if so, determining the degree of the unfavorable condition, wherein unfavorable conditions include at least one of the angle of the direction of the detected face, the effect of a lighting environment of the detected face, a worn article on the detected face, and the entropy of each partial area of the detected face; a feature value obtainment unit for obtaining a plurality of feature values from the detected face for respective designated partial areas; a reliability determination unit for determining reliability for each feature value of the respective designated partial areas based on the results obtained by the state determination unit including the degree of unfavorable conditions, and predetermined reliability tables stored on a reliability storage unit, the reliability storage tables containing reliability values for respective designated partial areas under various degrees of unfavorable conditions; and an identification unit for identifying the detected face with the face of the registrant stored on the storage unit by comparing the plurality of feature values stored on the storage unit for the respective partial areas of the face image of the registrant with the plurality of feature values obtained from the designated partial areas, while taking into account the reliability of each feature value of the designated partial areas; wherein the identification unit calculates a score of each partial area for the registrant by comparing the feature values of the plurality of partial areas of the registrant stored on the storage unit with the feature values obtained by the feature value obtainment unit for the designated partial areas and based on the score and the reliability of each of the partial areas, identifies the detected face with the face of the registrant stored on the storage unit.