To provide a vertical suction type concrete force-feed pump which can deal with even concrete with a small slump value and concrete containing aggregate with a large maximum grain size, while avoiding separation of the concrete during force-feeding.

In the bottom wall of a hopper 12 storing concrete to be force- fed, through openings 16, 18 are formed in symmetrical positions each spaced from the centerline V-V of the bottom wall by a predetermined distance (d), and a pair of concrete cylinders 20, 22 extending away from the bottom wall and fixed in place are provided. A pipe 24 with which upper and lower openings are communicated is freely rotatably placed within the hopper 12 with the centerline of the upper opening 24a aligned with the centerline V-V of the bottom wall, and with the centerline of the lower opening 24b rotated at a distance (d) from the centerline V-V. A drive mechanism which positions the lower opening immediately above the through openings 16, 18 alternately so that the lower opening can be aligned with the through openings 16, 18 is provided.