A manufacturing method for a composite sheet which includes: conveying a first continuous sheet in a first direction so as to abut a depressed surface of a mold member; forming an absorbent body by depositing liquid-absorbent particles on a portion of the first sheet proximal to a suction hole of the mold; and joining a second sheet over the first sheet having the absorbent body that is deposited therebetween, the second sheet being continuously transported in the first direction. A plurality of opposed slope members guide the liquid-absorbent particles onto the first sheet located on the mold member. At least one of the plurality of slope members causes the liquid-absorbent particles to reverse their falling direction from an upper slope member.