PURPOSE: To reduce the total tower height and the installation cost as well as enhance the liquid distribution effect by a method wherein, in a mass transfer tower provided with plural transfer divisions, plural stage branched pipe groups connected at right angle to an assembling pipe located at the center of the tower for distributing a liquid to each division and extend to a horizontal direction are arranged.

CONSTITUTION: In the mass transfer tower 1 provided with plural material transfer divisions 2a, 2b by interposing a space 3 within which a liquid and a gaseous medium are flowed counter-currently, a main pipe 9 extending to a horizontal direction and upper and lower branched pipe groups 10a..., 10b... which are connected to said main pipe 9 at right angle and have many small holes at the lower side portion thereof are arranged to a lower end portion of a collecting pipe 7 of a liquid distributor between each division comprising a parallel guiding members 4..., receiving troughs 5, a trough assemblage 6, assembling pipes 7 or the like. Thereby, the uniform liquid distribution can be easily attained even if a width of variation of the liquid amount is large and the height of the tower can be reduced and the installation cost is saved.