PURPOSE: To obtain the automatic building cleaning device which can satisfactorily clean the surface to be cleaned, prodded in a curved part on the wall surface of a building.

CONSTITUTION: A detector 25 provided in an automatic cleaning machine 8 detects whether the automatic cleaning machine 8 is positioned in a plane part or a curved part, and by the detecting signal, a controller 27 controls a vacuum pump 26, and a degree of vacuum in a cleaning head 11 is set so as to become high and low, in the curved part and the plane part, respectively. Accordingly, even in the course of cleaning the surface to be cleaned of the curved part, washing water is collected surely from the cleaning head and a satisfactory cleaning action can be obtained.