To provide an automatic cleaning device capable of performing cleaning only by one person without the need of making a worker climb up to a high place by attaching a bracket provided with a wipe-off blade and a detergent application member to the tip of an extendable/contractible boom provided with a driving means.

A base 5 is pivotally supported by a rotary shaft 4 horizontally disposed to a truck 2 and the driving means 8 incorporating a hydraulic mechanism and a control circuit, etc., is arranged. The extendable/contractible boom 9 is vertically erected on the driving means 8 and the outermost cylinder is pivotally supported by a falling prevention leg 10. To the tip of the extendable/ contractible boom 9, the detergent application member 21 and the wipe-off blade 22 are attached through the bracket 20. At the time of use, falling is prevented by opening the falling prevention leg 10 and the extendable/ contractible boom 9 is extended to a required height by operating the driving means 8. Then, after the base 5 is inclined and the detergent application member 20 and the wipe-off blade 22 are brought into contact with a glass window, the extendable/contractible boom 9 is contracted, the wipe-off blade 22 is lowered while being along the glass window, and the glass window is cleaned.