The focus of the research in ontologies shifts from ontology representation to ontology evolution perspectives that become an important field of ontology research. Even though ontology refers to specification of conceptualisation that provides a useful way to represent the semantics of the Web resources, there is a still need for maintaining and handling ontologies. Because ontologies may change as a result of accepting new information, when this occurs, ontology needs to be revised. However the new information may contradict what was initially defined in the ontology when ontology revision is performed. To discuss this revision perspective, this research proposes an approach based on the belief revision theory to revise ontologies. Three operators of expansion, revision and contraction are proposed to revise ontology to ensure that consistency of ontologies is maintained.