PURPOSE: To measure the collision charge quantity when a powdery and granular material repeats contact and separation and the effect of the conveying speed with easy actions by measuring the charge quantity generated when a sample is put from one end of charge detecting means into contact with many detecting means.

CONSTITUTION: A removable net is fitted between charge detecting pipes 131-135 made of a metal tube and connected in sequence from above and an insulating pipe 14 to adjust the contact and separation of a sample with the charge detecting pipes 131-135. The change of the charge quantity of the sample due to the mesh of the net can be measured. When the powdery and granular sample is put into a sample conveyance passage 15 from the upper end section of a sample guide pipe 11, the sample is dropped in the passage 15 at the prescribed sucking speed, and it is sucked into a sucking device 22 via a suction pipe 21 while repeating the contact and separation with the charge detecting pipes 131-135 and net. The charge quantity charged on the detecting pipes 131-135 and net is measured by a charge quantity detecting gauge 31 via a lead wire 32, and the collision charge quantity of the sample is obtained.