According to the present invention, disclosed is a full automatic dry-type suctioning device for a dental unit chair. The full automatic dry-type suctioning device of the present invention comprises: an air compressor having an air suctioning port and a discharging port； and a cyclone centrifuging means having a top end connected with the air suctioning port of the air compressor, having a top end circumference connected with a suctioning tip of a unit chair, and separating and removing waste water including foreign materials suctioned from the oral cavity of a patient from air. The cyclone centrifuging means comprises: a cyclone gas and liquid separator having a top end connected with the air suctioning port of the air compressor, having a top end circumference connected with the suctioning tip of the unit chair, and having a bottom end having a cone unit disposed thereon to have a foreign material discharging port； a foreign material storage having a feeding port disposed at the top end thereof to be connected with the foreign material discharging port of the cyclone gas and liquid separator, and having a discharging port disposed at the bottom end thereof； a branch pipe having both ends respectively connected to the foreign material discharging port of the cyclone gas and liquid separator and the discharging port of the foreign material storage through a three way valve； and an exhaust pipe for connecting the branch pipe and the discharging port of the air compressor. The present invention ensures a vacuum state in a unit chair by using an air compressor, so the consumption of water can be completely prevented during a diagnosis compared to a generally-used water closing-type vacuum pump. Also, foreign materials such as saliva and bloody pus suctioned from the oral cavity of a patient are certainly separated from air. Thus, the vacuum pump can be effectively prevented from being contaminated. The separated foreign materials can be automatically discharged while a
