Decantation and solvent extraction are applied to remove the solid particles from coal tar. In the production of coal tar pitch for carbon fiber, further treatment such as filtration is necessary in order to remove fine solid particles from coal tar. In this report, change in the filtration resistance was studied by changing filtration temperatures, pressures and pore size of filter. And also, that of the resistance was analyzed with Darcy's equation. These results are summarized as follows.(1) The experimentally obtained filtration curve shows a good agreement with Darcy's equation.(2) No change in the filtration resistance of the cake is found in the different filtration temperatures. This result means that the filtration rate increases at higher temperatures, since the viscosity of tar becomes much lower with the increase of temperature.(3) The filtration resistance of the cake is dependent on the filtration pressure. The cake shows the compressive property.(4) There is no difference in the filtration resistance according to the pore size of the filter.