PROBLEM TO BE SOLVED: To provide an unmanned travel work vehicle capable of reducing a labor which a user requires for setting of an area where an unmanned travel work vehicle performs a work.SOLUTION: An unmanned travel work vehicle which automatically performs a work in a prescribed work area comprises: a behavior acquisition part for acquiring behavior information containing a distance and a direction in which the unmanned travel work vehicle moved； an image analysis part for extracting a landmark 71 included in an image photographed by a camera which is provided on the unmanned travel work vehicle 10； and a surveying part for acquiring positional information of the landmark extracted by the image analysis part by a triangulation method. The surveying part acquires positional information of the landmark using a first angle which is an angular difference between a direction designating the land mark from a first point where the unmanned travel work vehicle passes when moving a constant movement direction, and a movement direction, a second angle which is an angular difference between a direction designating the landmark from a second point where the unmanned travel work vehicle passes when moving the constant movement direction, and the movement direction, and a distance between first and second points, and the surveying part determines the first point and/or second point so that the angular difference between the first angle and second angle approximates 90 degree while the unmanned travel work vehicle moves in the movement direction.SELECTED DRAWING: Figure 5【課題】無人走行作業車が作業を行うエリアの設定にかかるユーザーの労力を軽減可能な無人走行作業車を提供する。【解決手段】所定の作業エリア内で自動的に作業を行う無人走行作業車は、移動した距離及び方向を含む挙動情報を取得する挙動取得部と、無人走行作業車１０に設けられているカメラが撮像する画像に含まれる標識７１を抽出する画像解析部と、画像解析部が抽出した標識の位置情報を三角測量法によって取得する測量部とを備え、測量部は、無人走行作業車が一定の移動方向に移動する間に通る、第１地点から標識を指す方向と移動方向との角度差である第１角度と、第２地点から標識を指す方向と移動方向との角度差である第２角度と、第１地点と第２地点との距離とを用いて標識の位置情報を取得し、測量部は、無人走行作業車が移動方向に移動する間に、第１角度と第２角度との角度差が９０ｄｅｇに近づくように、第１地点及び／又は第２地点を決定する。【選択図】図５
