A particle counter has a saturator inhaling air in an atmosphere and vaporizing a working liquid therein; and an electrical detection unit electrically shielding an internal space thereof to maintain a temperature of the space to be constant, the air and vaporized working liquid flowing into the electrical detection unit through a side thereof from the saturator, condensing the vaporized working liquid on surfaces of ultrafine particles contained in the air, and charging the particles to measure a current of the charged particles, thereby measuring the number of the particles included in the air. According to the invention, it is possible to measure the number concentration of the ultrafine particles included in the air, and it is easy to move the counter depending on the measurement locations.

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