A particulate matter collecting apparatus includes a duct, a water sprayer, a micro-channel forming unit, and an impactor. A gas-liquid mixed fluid is formed by spraying water to air flowing along the inside of the duct using the water sprayer. The gas-liquid mixed fluid collides with a collision plate of the impactor after passing through a plurality of micro-channels provided in the micro-channel forming unit. Particulate matter in air is collected by droplets or a liquid film formed on the plurality of micro-channels and the collision plate. Water flowing down from the plurality of micro-channels is discharged through a first water outlet.