An inside regular filler layer is disposed inside a pipe where heat is exchanged between an inside and an outside of a pipe wall so as to abut an inner peripheral surface of the pipe, and an outside regular filler layer is disposed outside the pipe so as to surround the pipe and closely contact an outer peripheral surface of the pipe. The outer peripheral surface of the pipe is subjected to close contact-promoting processing in order to enhance close contacting feature between the outer peripheral surface and the outside regular filler layer. The pipe/filler unit is used for the distillation section of an internal heat exchanging type distillation column.