An anti-disassembling device for an electronic product includes a case, a linear movement device, a circular movement device and an optical encoder. At least one retractable transmission member is connected to the case. The circular movement device is located in the case and has an encoding disk, which has multiple slots defined therethrough and teeth are defined in the periphery thereof. The at least one retractable transmission member is engaged with the teeth to rotate the encoding disk. The optical encoder has a lighting module which emits light beams through the slots of the encoding disk and a photosensitive module receives the light beams and sends a signal to the storage unit of the electronic product. The retractable device rotates when the electronic product is disassembled.