An image processing device comprising: a generating unit that is configured to generate, based on a distance image, two-dimensional distribution information indicating a two-dimensional distribution of an object, in which a distance in a horizontal direction, a distance in a depth direction, and a frequency value corresponding to the distance in the horizontal direction and the distance in the depth direction are related; and a labeling unit that is configured to conduct a labeling process by conducting search on the two-dimensional distribution information multiple times on a column-by-column basis from an outer side of the two-dimensional distribution information, detecting a first pixel having the frequency value that is more than a predetermined threshold during each search, and assigning a label that is different in each time of search, wherein the labeling unit is configured to conduct a first labeling process by selecting the first pixel from pixels that abut a pixel being searched in a search direction and assigning the label to the selected first pixel when the label is not assigned to the selected first pixel and further configured to conduct the first labeling process by conducting further search in the depth direction, selecting a second pixel having a largest frequency value from a plurality of pixels that are searched and consist of a pixel being positioned in the depth direction in relation to the first pixel and a pixel being positioned on right and left sides of the pixel being positioned in the depth direction, and assigning the label when the label is not assigned to the selected second pixel, wherein the image processing device comprises a detecting unit that is configured to detect an object that is curved as it stretches in the depth direction of the two-dimensional distribution information from the two-dimensional distribution by regarding pixels with the identical label assigned thereto as pixels of an identical object. a generating unit that is configured to generate, based on a distance image, two-dimensional distribution information indicating a two-dimensional distribution of an object, in which a distance in a horizontal direction, a distance in a depth direction, and a frequency value corresponding to the distance in the horizontal direction and the distance in the depth direction are related; and a labeling unit that is configured to conduct a labeling process by conducting search on the two-dimensional distribution information multiple times on a column-by-column basis from an outer side of the two-dimensional distribution information, detecting a first pixel having the frequency value that is more than a predetermined threshold during each search, and assigning a label that is different in each time of search, wherein the labeling unit is configured to conduct a first labeling process by selecting the first pixel from pixels that abut a pixel being searched in a search direction and assigning the label to the selected first pixel when the label is not assigned to the selected first pixel and further configured to conduct the first labeling process by conducting further search in the depth direction, selecting a second pixel having a largest frequency value from a plurality of pixels that are searched and consist of a pixel being positioned in the depth direction in relation to the first pixel and a pixel being positioned on right and left sides of the pixel being positioned in the depth direction, and assigning the label when the label is not assigned to the selected second pixel, wherein the image processing device comprises a detecting unit that is configured to detect an object that is curved as it stretches in the depth direction of the two-dimensional distribution information from the two-dimensional distribution by regarding pixels with the identical label assigned thereto as pixels of an identical object.