A device for detecting particulates includes: a filter; a filter container; an upstream pipe; a downstream pipe; an upstream detecting unit; and a downstream detecting unit. The upstream detecting unit has a branch flow route for receiving gas from the upstream pipe, a trapping portion, a transmitting portion for transmitting an electromagnetic wave to the trapping portion, and a receiving portion for receiving an electromagnetic wave from the trapping portion. The downstream detecting unit has a branch flow route for receiving gas from the downstream pipe, a trapping portion, a transmitting portion for transmitting an electromagnetic wave to the trapping portion, and a receiving portion for receiving an electromagnetic wave from the trapping portion. The amount of the particulates trapped in the filter is detected based on a difference between detection values of the mass of the particulates trapped in the upstream and downstream trapping portions.