Floating particle detection device

A floating particle detection device (1) is capable of achieving a simplified device structure and accurately determining a floating particle type and is provided with a laser light irradiation unit (10) including a laser light emission element (11) and a back monitor light reception element (12), a scattered light reception unit (20) for selectively receiving light having a predetermined polarization component from among the scattered light generated when floating particles (50) are irradiated and generating a second detection signal, and a determination processing unit (30) for determining the floating particle type on the basis of a first detection signal and the second detection signal. The incident light incident on the back monitor light reception element (12) includes back monitor laser light (L0) and, from among the scattered light (Ls) of the irradiation laser light (L1) irradiated onto the floating particles (50), backscattered light (Lbs) directed toward the laser light irradiation unit (10).