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).