Intraoral radiography is one of the most important techniques for dentists, which is commonly used to diagnose dental caries and gum disease. An intraoral radiograph shows a perspective projection image of the teeth of patient, so that the roentgenogram is affected by the positional relationship between film, teeth, and indicator cone which directs X-ray radiation toward the film. In order to administer intraoral radiography for a patient, he/she has to have a small X-ray film inserted in their oral cavity. The position and orientation of the film are properly adjusted by the dentist or radiologic technician. And then, the indicator cone is positioned outside the patient's mouth, and its orientation is determined depending on the teeth and film. Recently, it has been reported that the skill of intraoral radiography of dental students and interns are declining in Japan. The background of this issue is that the conventional training method needs to use an actual X-ray machine and lots of film, and much time to develop the roentgenogram. We assumed that these training inefficiencies would be improved by using virtual reality technique. In this paper, we propose a training simulator for intraoral radiography based on virtual reality, where the trainees quickly obtain a graphical image of intraoral radiograph on a computer display after the setting of film and indicator cone is finished. This paper presents a simulation algorithm for generating a graphical image of intraoral radiograph, and discusses about optimum design of an indicator cone positioning device for the simulator. Simulation results show that the proposed simulation algorithm provides realistic observations of intraoral radiograph.