a first joining of joining a first elastic strip member to a sheet by feeding and surface-contccting the continuous body of the first elastic strip member to the continuous body of the sheet, via a first oscillating arm that oscillates in a direction intersecting the transporting direction with a first spindle portion as a swivel center a second joining of joining a second elastic strip member to the sheet by feeding and surface-contccting the continuous body of the second elastic strip member to the continuous body of the sheet, via a second oscillating arm that oscillates in a direction intersecting the transporting direction with a second spindle portion as a swivel center, wherein in the first joining, the first elastic strip member supplied toward the first spindle portion side roller of a first oscillating arm is subsequently put around an outer circumferentall face of the first spindle portion side roller and an outer circumfereniial face of the first oscillating end side roller of the first oscillating arm, and, after being reversed in a travel direction with the first oscillating end side roller, is placed on the continuous body of the sheet and joined thereon, wherein in the second joining, 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 the second spindle portion side roller and an outer circumferentall face of the second oscillating end side roller of the second oscillating arm, and, after being reversed in the travel direction with the second oscillating end side roller, is placed on the continuous body of the sheet and joined thereon, wherein a first placing position where the contnnuous body of the first elastic strip member is to be placed on the contnnuous body of the sheet with the first oscillating arm and a second placing position where the contnnuous body of the second elastic strip member is to be placed on the contnnuo
