An image processing apparatus captures a target image containing marker images and a recognition target range identified by a marker-image set including at least parts of the marker images. The image processing apparatus includes an image capturing section, a first detection section, a position estimation section and a second detection section. The first detection section detects one marker image as a reference marker image from a captured image. The position estimation section adopts a marker image, which is other than the reference marker image and is contained in at least one of marker-image sets containing the reference marker image, as a corresponding marker image. The position estimation section estimates a position of the corresponding marker image in the captured image based on a size of the detected reference marker image. The second detection section detects the corresponding marker image based on the estimated position of the corresponding marker image.