An ophthalmological device comprising: a memory that stores a three dimensional data set acquired by applying optical coherence tomography to a subject's eye; a color coding unit that assigns color information according to a depth position to the three dimensional data set; a layer region identifying unit that identifies a plurality of layer regions by applying segmentation to the three dimensional data set; a blood vessel region extracting unit that extracts a blood vessel region from each of the plurality of layer regions; a front image constructing unit that constructs a front image based on each of a plurality of blood vessel regions extracted by the blood vessel region extracting unit; and an image composing unit that composes at least two of a plurality of front images constructed by the front image constructing unit based on the color information, to construct a composite front image; a display controller that displays the composite front image on a display device based on the color information; an interested blood vessel region setting unit that sets an interested blood vessel region in the blood vessel region; and an operation unit that receives an operation for selecting two or more front images from among the plurality of front images, wherein the image composing unit receives a result of setting the interested blood vessel region from the interested blood vessel region setting unit, selects a front image in which the interested blood vessel region is depicted from front images different from the two or more front images, and changes pixel values of blood vessel regions other than the interested blood vessel region in the selected front image to default values, thereby obtaining the selected front image in which only the interested blood vessel region is depicted, and further composes the composite front image constructed based on the two or more front images and the selected front image in which only the interested blood vessel region is represented, and the display controller displays a composite front image constructed based on the two or more front images selected using the operation unit, on the display device, and displays a composite image of the composite front image constructed based on the two or more front images and the selected front image in which only the interested blood vessel region is depicted, on the display device. a memory that stores a three dimensional data set acquired by applying optical coherence tomography to a subject's eye; a color coding unit that assigns color information according to a depth position to the three dimensional data set; a layer region identifying unit that identifies a plurality of layer regions by applying segmentation to the three dimensional data set; a blood vessel region extracting unit that extracts a blood vessel region from each of the plurality of layer regions; a front image constructing unit that constructs a front image based on each of a plurality of blood vessel regions extracted by the blood vessel region extracting unit; and an image composing unit that composes at least two of a plurality of front images constructed by the front image constructing unit based on the color information, to construct a composite front image; a display controller that displays the composite front image on a display device based on the color information; an interested blood vessel region setting unit that sets an interested blood vessel region in the blood vessel region; and the image composing unit receives a result of setting the interested blood vessel region from the interested blood vessel region setting unit, selects a front image in which the interested blood vessel region is depicted from front images different from the two or more front images, and changes pixel values of blood vessel regions other than the interested blood vessel region in the selected front image to default values, thereby obtaining the selected front image in which only the interested blood vessel region is depicted, and further composes the composite front image constructed based on the two or more front images and the selected front image in which only the interested blood vessel region is represented, and the display controller displays a composite front image constructed based on the two or more front images selected using the operation unit, on the display device, and displays a composite image of the composite front image constructed based on the two or more front images and the selected front image in which only the interested blood vessel region is depicted, on the display device.