In developing large-scale products, it is important to review the design of products from multiple perspectives and to prevent inconsistency in design. Web-based information sharing is very promising for realizing efficient design reviews. In this paper, we propose a design review system based on 3D models shared on the Web. We call comments and locations defined on a 3D model as annotations. In our system, annotations on 3D models are stored in a client-server framework, and can be shared among the design team. We propose four types of annotation methods, which consist of billboards, direct 3D painting, 2D drawing on a snapshot, and feature extraction. Since all of them are defined using 2D strokes and transformation matrices, they can be very easily and interactively specified by reviewers. These annotated regions are associated with comments, and are shared by designers through network. We implemented our review system and applied it to 3D models represented in the VRML format.