This paper presents OntView, a new ontology visualization tool, to solve the visualization problem of ontology. Pointing out that existing ontology editors and visualization tools have difficulty in expressing the structure of large-scale ontologies meaningfully and concisely, OntView focuses on intuitively visualizing ontology concepts and formal definitions through a user-friendly interface. It follows the "What you see is what you meant" paradigm that shows inferred knowledge by utilizing DL inferrer, and provides the general concept inclusion (GCI) visualization function that existing tools do not have. In addition, to prevent information overload, it provides functions such as generating ontology summaries by evaluating importance based on various algorithms, focusing on TBox elements between two classes, and hiding and showing specific branches. OntView is open source.