Apparatus for mass transferring between phases different from each other

According to the present invention, in an apparatus for mass transferring between phases different from each other, tube plates are fixed to opposite opening ends of an outer tubular column having a fluid feeding nozzle and a fluid discharge nozzle, the tube plates are each formed therethrough with a through-hole for fixing a porous tube, the hole is formed over the entire peripheral wall thereof with a stepped portion such that an elastic member such as an O-ring can be easily provided. A tubular press-in member including an annular elastic member, a collar and the like are provided in the hole, into which the end portion of the porous tube is coupled, whereby the press-in member is pressed into a space formed between the hole wall and the porous tube wall so as to achieve sealing between the porous tube wall and the tube plate wall, so that the inner porous tube can be replaced by a new one simply, easily and quickly.