A first set-up portion (7) in the lower part of one knitted fabric (4) and a second set-up portion (6) in the lower part of another knitted fabric (2) are set up by a flat knitting machine that includes at least a pair of front and back needle beds (F, B) and a plurality of set-up needles (20). A first row of hooked stitches (10) and a second row of hooked stitches (12) that serve as rows of hooked stitches of the first set-up portion (7) are first knitted, and then a third row of hooked stitches (14) and a fourth row of hooked stitches (16) that serve as rows of hooked stitches of the second set-up portion (6) are knitted. A set-up yarn of the first row of hooked stitches (10) and the set-up yarn of the second row of hooked stitches (12) are intersected with each other between the front and back needle beds (F, B), and the set-up yarn of the third row of hooked stitches (14) and the set-up yarn of the fourth row of hooked stitches (16) are intersected with each other between the front and back needle beds (F, B). Thereafter, the intersections between the set-up yarn of the first row of hooked stitches (10) and the set-up yarn of the second row of hooked stitches (12) are held by the set-up needles (20) and the intersections between the set-up yarn of the third row of hooked stitches (14) and the set-up yarn of the fourth row of hooked stitches (16) are held by the set-up needles (20). Furthermore, hooked stitches of the third row of hooked stitches (14) and the fourth row of hooked stitches (16) that are positioned on one needle bed (B) are removed from this needle bed (B), and the remaining hooked stitches that are positioned on the other needle bed (F) are maintained, and hooked stitches of the first row of hooked stitches (10) and the second row of hooked stitches (12) that are positioned on the other needle bed (F) are removed from this needle bed (F) and the remaining hooked stitches that are positioned on the one needle bed (B) are maintained. Thereafter, stitches of the first set-up portion (7) are knitted on the hooked stitches of the first row of hooked stitches (10) and the second row of hooked stitches (12) that are positioned on the one needle bed (B), and stitches of the second set-up portion (6) are knitted on the hooked stitches of the third row of hooked stitches (14) and the fourth row of hooked stitches (16) that are positioned on the other needle bed (F). The front and back knitted fabrics are pulled down independently at the time of setting up.