PURPOSE: To sample a fixed quantity of soot and smoke accurately in the absence of an operator by sampling a fixed quantity of soot and smoke and immediately stopping a suction pump automatically.

CONSTITUTION: Soot and smoke are sucked from one end 3 of a sample collection tube 2 through operation of a vacuum pump 10. Soot and smoke are filtered when they pass through a cylindrical filtering paper attached to a filtering paper housing part 4. Filtered soot and smoke pass sequentially through a sulphurous acid gas suction bottle 7, a mist removing bottle 9 reaching a vacuum pump 10. Further they pass through an oily mist remover 11 to be followed by a process to measure a sampling quantity with the help of a gas meter 13. After this step, they are discharged out of the system through a gas meter outlet part 13b. The gas meter 13 is equipped with a luminous diode 20 and a phototransistor 21. When the meter 13 needle is turned to reach a prearranged position, an infrared ray irradiated by the luminous diode 20 is reflected by the needle to be irradiated to the phototransistor 21 with the generation of a pulse. This pulse is counted by means of a counter 34 and the needle of the meter 14 is turned by a prearranged number of revolutions. Further the sucked residual quantity of an indication part 36 stands at zero level, resulting in the stopping of a pump 10.