A manufacturing method for a composite sheet formed by sandwiching an absorbent body that absorbs liquid between a first sheet and a second sheet is provided. The method includes: conveying the first sheet with abutting a mold member on a surface of the mold member, the first sheet being continuous in a first direction, the mold member including a mold formed on the surface in a depressed shape and moving along the first direction perpendicular to a width direction of the surface forming the absorbent body using a procedure in which a liquid-absorbent particle falls towards the first sheet abutting the surface and the liquid-absorbent particle is deposited on a corresponding portion of the first sheet to the mold by suction from a suction hole of the mold and joining the second sheet and the first sheet with placing the second sheet over the first sheet, the first sheet having the absorbent body that is deposited thereon, the second sheet being continuously transported in the first direction. In the forming, a plurality of slope members having a slope is included in an up-and-down direction. A height of an upstream end of the slope and a height of a downstream end of the slope are different in the first direction. While the liquid-absorbent particle successively slides a slope of the plurality of slope members, the liquid-absorbent particle is distributed in the width direction and falls on the first sheet located on the mold member. At least one slope member of the plurality of slope members makes the liquid-absorbent particle reverse its sliding direction and slide, the liquid-absorbent particle falling from a slope member adjacent above the one slope member.
