The belt transfer system is one of the image transfer processes used in electrophotography. In this process, paper clings to the electro-resistive belt, and is stably fed through the processor. However, electrical discharge may occur between the paper and the belt when the paper is separated from the belt under particular conditions. This discharge is named “separating discharge”. Because this discharge causes image degradation, it is important to make clear the separating discharge phenomenon. A model experiment and numerical simulation of separating discharge are carried out for the study of such phenomena. When the sheet is charged at low electrification level, local strong discharge occurs intermittently. On the other hand, the separating discharge becomes continuous and weak when the sheet is charged at high electrification level. Toner movement due to the discharge is also numerically simulated using discrete element method, and the result shows that the image degradation occurs at low electrification level of the sheet, whereas it does not occur at high electrification.