The invention discloses a height adjusting device, which comprises a first airbag, a second airbag and at least one air control unit controlling air inlet and air outlet of the first airbag or the second airbag. The first airbag is provided with at least one airbag body in which an elastic body is arranged; the second airbag is arranged below the first airbag; and the second airbag is provided with at least one airbag body in which an elastic body is arranged. The device can make the second airbag change the height by means of the air control unit, and make the airbag body in the first airbag keep a preset pressure state; therefore, the surface of the airbag body is fluctuant and automatically adjusts the shape along different postures of a user so as to be completely fitted with parts of the user leaning against the airbag body, namely the head, the neck, the shoulder, the hip and the like, and the airbag body has high and low, softness and hardness, and shaping adjusting effects so as to completely meet human engineering and be convenient to carry and use. The invention also discloses a pad body employing the height adjusting device.