1. A moving-object position/attitude estimation apparatus for estimating a position and an attitude angle of a moving object, comprising: an image-capturing unit configured to acquire a captured image by capturing an image of surroundings of the moving object; a comparative image acquiring unit configured to acquire a comparative image viewed from a predetermined position at a predetermined attitude angle; a likelihood setting unit configured to compare the captured image acquired by the image-capturing unit with the comparative image acquired by the comparative image acquiring unit, and to assign a high attitude angle likelihood to the comparative image in a case where a distant-position pixel in the captured image matches a distant-position pixel in the comparative image and assign a high position likelihood to the comparative image in a case where a proximal-position pixel in the captured image matches a proximal-position pixel in the comparative image; and a moving-object position/attitude estimation unit configured to estimate the attitude angle of the moving object based on the attitude angle of the comparative image assigned the high attitude angle likelihood by the likelihood setting unit and estimate the position of the moving object based on the position of the comparative image assigned the high position likelihood by the likelihood setting unit.