The present invention relates to an automatic pressing abdominal support, and more specifically, to an automatic pressing abdominal support which is capable of solving a problem generated as the circumference of the waist is being immediately strongly pressed by an existing pressing abdominal support of which length is not changed when the wearer wears the abdominal support once in the case that the users abdomen is expanded: by tightening the circumference of waist according to a value set in a control part when a pressing signal is inputted into the control part in a state that a user loosely wears the automatic pressing abdominal support around his or her waist circumference； enabling the wearers waist circumference to be tightened to a predetermined pressure while the length of a main body of the abdominal support is being relaxed as much as the wearers abdomen is expanded by a spring-embedded tension adjuster, when the wearer bends his or her waist to lift a heavy object or the abdomen is expanded by the movements of the body including coughing and others； and enabling the abdominal support to tighten the waist circumference as the length of the abdominal support main body is shrunk as long as an initially set length by a spring, when the expanded abdomen is contracted to its original position. An automatic pressing abdominal support (100) according to the present invention comprises: a band type abdominal support main body (10) which has a female buckle (11) installed at one end thereof, and which is installed such that other end of the abdominal support main body (10) is connected to the tension adjuster (30)； a band length stretcher (20) which is installed at a middle portion of the abdominal support main body (10), and winds or unwinds the abdominal support main body (10) to extend or shrink a length of the abdominal support main body (10)； the tension adjuster (30) of which one end is detachably connected to the female buckle (11) of the abdominal support
