A disparity deriving apparatus for deriving disparity of an object based on a captured reference image of the object and a captured comparison image of the object includes a calculator to calculate costs between a first reference area in the reference image and each one of corresponding areas in the comparison image, and costs between a second reference area and each one of corresponding areas corresponding to the second reference area in the comparison image; a synthesizer to synthesize the costs of the first reference area, and the costs of the second reference area as synthesis costs; a deriving unit to derive a disparity value of the object captured in the first reference area based on the synthesized synthesis cost; and an output unit to output the derived disparity value and a specific cost of the first reference area identified by the derived disparity value.