The present invention relates to a mutated tau protein fragment and a use thereof. The mutated tau protein fragment of the present invention consists of 12 amino acids and thus can easily be prepared. In addition, when the mutated tau protein fragment is injected into an individual as an antigen, a neutralizing antibody against the mutated tau protein is generated. Moreover, the mutated tau protein fragment reduces the aggregation of abnormal tau proteins. Accordingly, the mutated tau protein fragment of the present invention can be effectively used for the prevention or treatment of degenerative neurological diseases.