Provided is an apparatus for reducing a thickness of an absorbent body having liquid absorbent fiber as a main material. The apparatus includes a pressing device that reduces the thickness of the absorbent body transported in a transport direction, by sandwiching and pressing the absorbent body in a thickness direction orthogonal to the transport direction, a pair of rollers that is positioned on a downstream side along the transport direction than the pressing device, and rotates while passing the absorbent body through a gap formed by outer circumferences of the pair of rollers opposing each other, a sensor that outputs measurement information relating to the thickness of the absorbent body at a position between the pressing device and the pair of rollers, and a controller that sets a size of the gap between the pair of rollers based on the measurement information.
