PURPOSE: To easily and rapidly remove a concrete clog by rotating the rotating rotor for squeezing of a concrete pump in an opposite direction when concrete clogs a pumping tube or concrete transport pipe.

CONSTITUTION: When concrete causes a clog in the course of a pumping tube 3 or a pipe in the state where a concrete pump 1 having a hydraulic motor 5 for rotating a rotating roller 2 circulated while squeezing the pumping tube 3 is driven to force feed the concrete, the rotation of the hydraulic motor 5 is lowered or stopped, and the oil pressure of the hydraulic motor 5 is raised. When a pressure switch 6 is operated by this rise, an electromagnetic switching valve 10 is switched through a control circuit 11, and a pilot oil is sent to a servo valve 8 and a hydraulic pump valve 7 to operate the hydraulic pump 7 in the opposite direction, and the hydraulic motor 5 is quickly reversed plural times. Thus, the concrete clog is removed.