The present invention provides a quantitative catalyst supply device that supplies a predetermined amount of catalyst slurry through an injection port formed through a container bottom. The quantitative catalyst supply device includes: an extendible supply pipe connected to a hopper and filled with catalyst slurry; a head connected to the supply pipe and supplying catalyst slurry to the injection port at the container bottom; a cylinder connected to a side of the supply pipe and supplying a predetermined amount of catalyst slurry through the head; and valve units disposed in an upper portion and a lower portion of the supply pipe spaced from the cylinder and opened or closed by operation of the cylinder.