An automatic air control structure for an airbag can be applied to pillows, cushions and so on and comprises a plurality of valve bodies, at least one airbag and at least one air tube, wherein an elastic piece is arranged in the airbag; the valve bodies have valve structures; by using the valve bodies, the air can freely enter into and exit from the airbag and adjust the pressure of the airbag; the air tube communicates with the airbag and the valve bodies; the positive and negative pressures of the airbag are adjusted and balanced by using the valve bodies and atmospheric pressure, so that the height, the softness and the shape of the airbag are automatically adjusted according to the level of the pressure (such as head, neck and hip) to reduce the reacting force of the airbag; therefore, the propping part (such as head, neck and hip) is naturally and comfortably supported; and moreover, after the pressure on the airbag disappears, the airbag can be automatically inflated to recover to the original shape, so that the elasticity fatigue and deformation of the elastic piece can be avoided.