PURPOSE: To obtain a siphon type sludge sucking machine with trouble-free and highly reliable characteristics, by mechanically performing a turning motion of a sucking pipe at the end of a sedimentation tank in connection with a traveling of said machine.

CONSTITUTION: When a sludge sucking machine 4 travels in the direction of an arrow-marked chain line, a horizontal part (5b) of a sucking pipe is kept in a state projecting to the right side of a figure to discharge a sludge of a sludge gathering trough 2a locating at the right side from a sucking and discharging pipe 6 to the outside through a discharging channel 14. When the machine 4 comes to the vicinity of the end of straight trough 2a, a sucking pipe 5 turns anticlockwise around a central pipe part 5a with the traveling of the machine 4, since a backplate of an action lever 15 touches a stopper 17, and then a roller mechanism 16 touches a guide plate 18 to separate the lever 15 from the stopper 17. Hereafter, with the traveling of the machine 4 to the terminal (b), the pipe 5 keeps turning while being press-guided by a guiding plate 12, and then the machine takes a switchback posture to travel to the reverse direction.