A method that makes a thickness of an absorbent body (1), including a liquid absorbent fiber (2) and a superabsorbent polymer (5), thin, the method includes: 1. transporting the absorbent body by moving a holding surface (21) while holding the absorbent body on the holding surface with suction air from a suction hole (22) on the holding surface, and 2. Making the thickness of the absorbent body thin by sucking a belt member (53) towards the holding surface using the suction air from the suction hole, in a predetermined range of a travel path of the holding surface, the belt member being arranged opposing the holding surface along the travel path and being arranged movably along the travel path over the predetermined range of the travel path, and sandwiching the absorbent body between the holding surface and the belt member. Fig. 6
