An image processing device, with reference to tomographic data obtained using a sensor moving in a lumen of a biological tissue, displays an image representing the biological tissue on a display, and includes a control unit that acquires specification data specifying at least one location in a space corresponding to the tomographic data, identifies a direction of the at least one location from a centroid in a cross section of the biological tissue orthogonal to a movement direction of the sensor, the direction including the at least one location, as a specification direction, with reference to the tomographic data, identifies a position corresponding to the at least one location in the cross section as a corresponding position according to an identified specification direction and a position of the centroid, and performs control so that a mark is displayed at an identified corresponding position when the image is displayed.