PROBLEM TO BE SOLVED: To satisfy a demand of high electric field intensity that is perpendicular to the ion drift direction for improving the skirting of the generation of a short pulse of an ion segment, and satisfy a demand of a parallel electric field so as to make the same ion trajectory to obtain a high resolution. SOLUTION: In the ion mobility spectrometer having an ionization region to generate the ion, a reaction room which is adjacent to the ionization region and which is installed so that the ion generated in the ionization region and a carrier gas containing a sample to detect components are made to react, and a drift region constituted of electrodes to demarcate a constant electric field to move the ion reacted in the reaction room, in order to cut out the ion into a short-time pulse state from the reaction room to the drift region, two neighboring electrodes are arranged at the boundary of the reaction room and the drift region. COPYRIGHT: (C)2005,JPO&NCIPI
