A method of manufacturing a composite sheet includes joining a first elastic strip member to a sheet by feeding and surface-contacting the first elastic strip member to a continuous body of the sheet； and joining a second elastic strip member to the sheet by feeding and surface-contacting the second elastic strip member to the continuous body. The first elastic strip member supplied toward a first spindle portion side roller is subsequently put around an outer circumferential face of the first spindle portion side roller and an outer circumferential face of a first oscillating end side roller. The second elastic strip member supplied toward the second spindle portion side roller of a second oscillating arm is subsequently put around an outer circumferential face of a second spindle portion side roller and an outer circumferential face of the second oscillating end side roller of the second oscillating arm.
