PARTICLE CONCENTRATION DETECTION DEVICE

The present invention provides a particle concentration detection device for detecting a concentration of a particulate matter contained in air outside a vehicle compartment, comprising: a case member (21) forming an air passage (24) through which the air outside the vehicle compartment flows; a concentration detection unit (51) for detecting the concentration of the particulate matter contained in the air outside the vehicle compartment and flowing through the air passage; and a sensor case (52) accommodating the concentration detection unit. The sensor case has a sensor inlet (521) for introducing the air outside the vehicle compartment from the air passage into the sensor case, and a sensor outlet (522) for allowing air inside the sensor case to flow out of the sensor case and into the air passage. Each of the sensor inlet and the sensor outlet opens toward the air passage formed by the case member. 对车室外的空气所含的颗粒状物质的浓度进行检测的颗粒浓度检测装置具备：壳体部件(21)，该壳体部件形成供所述车室外的空气流动的空气通路(24)；浓度检测部(51)，该浓度检测部对在所述空气通路流动的所述车室外的空气所含