A computer case including a body, a first rear window, a blocking panel, and a plurality of exchangeable modules is provided. The body has a containing opening. The first rear window is assembled to the body and is located within the containing opening, and the first rear window has a module opening and a blocking panel opening. One of the exchangeable modules is assembled to the first rear window. The blocking panel is assembled to the first rear window and is located within the blocking panel opening, and the blocking panel has a plurality of connector openings.