PURPOSE: To suppress the invasion of fine particles from a running pipeline into the clean room by providing a pressure regulating mechanism, reducing a pressure in a loading pipeline section to a value lower than the internal pressure of the clean room.

CONSTITUTION: Goods are supplied or taken out under a condition that a door 2 is opened after the opening operation of first airflow intercepting gate G1 and the pressure in the loading pipe section (l) is reduced by the suction of a blower 20 to a pressure lower than the pressure in the clean room, thereby flowing the air in the clean room A into the loading pipeline section (l). A purifying device K, effecting with respect to the piepline section (l), is constituted of a ventilating hole 24b, communicating with the discharging port 23b of a fan 22 arranged below the loading pipeline section (l) and formed on the upper part of the side wall of the pipeline section (l), and a HEPA filter 25 provided in the communicating flow path between the discharging port 23b and the ventilating hole 24b. Accordingly, the invasion of the fine particles in the running pipeline L into the clean room A may be suppressed surely by opening the door 2 after the inside of the pipeline section (l) is cleaned.