A fine particle count detector 10 is provided with a charge generating element, a capturing device, and a count measurement device. The charge generating element imparts a charge generated by electric discharge to fine particles in a gas introduced into a ventilation pipe 12 and makes the fine particles charged fine particles. The capturing device captures the charged fine particles on a capturing electrode 48 using an electric field generated by an electric field generating unit 42. The count measurement device detects the number of charged fine particles on the basis of a physical quantity of the capturing electrode 48 that varies according to the number of charged fine particles captured by the capturing electrode 48. Here, the ventilation pipe 12 is provided with dense skeleton-forming parts 13 (13a-13d) formed from a ceramic material, and dense stress-relieving parts 14 (14a-14d) in contact with the skeleton-forming parts 13 and formed from a material having a lower Young's modulus than the ceramic mater
