We propose a software requirements analysis method based on domain ontology technique, where we can establish a mapping between a software requirements specification and the domain ontology that represents semantic components. Our ontology system consists of a thesaurus and inference rules and the thesaurus part comprises domain specific concepts and relationships suitable for semantic processing. It allows requirements engineers to analyze a requirements specification with respect to the semantics of the application domain. More concretely, we demonstrate following three kinds of semantic processing through a case study, (1) detecting incompleteness and inconsistency included in a requirements specification, (2) measuring the quality of a specification with respect to its meaning and (3) predicting requirements changes based on semantic analysis on a change history.