PURPOSE: An apparatus and a method of preparing catalyst for synthesizing carbon nano-tube are provided to collect catalyst based on the size of particles in a catalyst collecting process. CONSTITUTION: An apparatus of preparing catalyst for synthesizing carbon nano-tube includes a reactor(110), a heating part(120), a nozzle(130), a first collecting part(210), and a second collecting part(220). The reactor arranged a space in which the spraying type pyrolysis process of a catalytic solution is implemented. The heating part heats the reactor. The nozzle sprays the catalytic solution into the reactor. The first collecting part collects catalytic particles formed in the reactor based on the size of the particles. The second collecting part collects remained catalytic particles through the first collecting part.