PURPOSE: To prevent the adheson of high-temperature fine powders on an opening section opened into a high-temperature fine-powder flow path at one end of a drawing pipe without requiring a special device and labor hours.

CONSTITUTION: A high-temperature fine-powder flow path 1, in which high- temperature fine powders flow at negative pressure by suction, a drawing pipe 3, in which one end is opened to the pipe wall 2 of the high-temperature fine- powder flow path 1, a closing plug 19, which is mounted at the other end of the drawing pipe 3 and to which an outside-air introducing hole 18 is bored, and a lead piping 5 branched from the intermediate section of the drawing pipe 3 and connected to a differential pressure gauge 7 are provided. The outside air introduced from the outside-air introducing hole 18 flows into the high- temperature fine-powder flow path 1, thus preventing the adhesion of high- temperature fine powders near an opening section 16.