Condenstation particle counter

A condensation particle counter is capable of efficiently measuring the number and size of fine particles. The condensation particle counter includes a saturator (10), a condenser (20) and an optical particle counter (30). The saturator (10) is designed to generate a saturated gas by saturating a gas in which fine particles are suspended with working fluid. The condenser (20) is connected to a downstream side of the saturator to condense the saturated gas so that liquid droplets can grow around the fine particles. The optical particle counter (30) is connected to downstream sides of the condenser to optically detect the liquid droplets supplied from the condensers. The condenser (20) has a condenser tube (21) for interconnecting the saturator (10) and the optical particle counter (30). The present condensation particle counter can use water as working fluid and also can optically measure fine particles in an easy and accurate manner by forming or installing an inner surface of a condenser tube with a hydrophilic tube (23).