To prevent disruption of attraction even if there is a crack by arranging separate a ttracting chambers in a plurality in all directions in a wall surface attracting surface.
An attracting unit 1 is formed by connecting parallel crawler belts 2 having a large number of suckers 13 to each other by an arm 8, and the suckers 13 are formed so that attracting chambers exist in a plurality in all directions. Therefore, even if there is a factor of disrupting attraction such as a long crack, they can reliably satisfy an attracting function as a wall cleaner. Since a part striking on a sprocket of the crawler belts 2 becomes independent suckers 13, outer peripheral parts of the crawler belts 2 are not damaged by being pulled by a position striking on the sprocket.