An image based touch apparatus and its control method are provided. The image based touch apparatus includes at least two region indicators, at least one image capturing apparatus, and a processing apparatus. Each region indicator includes indication units for indicating a touch surface and a touch sensor. The image capturing apparatus captures at least one image including the indication units. The processing apparatus is connected to the image capturing apparatus and configured for receiving the image. In the method, the touch surface is identified by the processing apparatus according to the indication units in the image. If a touch sensor detects an operating object touches the touch surface, the indication units of the region indicators generates a touch message. The processing apparatus determines the touch message according to the image and then determines a position of the operating object on the touch surface according to the image.