A method for preventing unraveling of a knitting yarn at a yarn-in portion or a yarn-out portion when knitting a knitted fabric having at least one of the yarn-in portion and the yarn-out portion where knitting yarns are switched in the middle of knitting the knitted fabric using a flat knitting machine, which includes at least a pair of a front and a back needle bed (FB, BB) and in which either one of the front and back needle beds is capable of being racked in a traverse direction; the method being characterized by: step α of knitting a first stitch row including a first stitch, a second stitch, and a third stitch continuing in a knitting width direction so as to satisfying requirement or, arranging the first stitch and the third stitch of the first stitch, the second stitch, and the third stitch on one needle bed and the second stitch on the other needle bed, arranging the second stitch and the third stitch of the first stitch, the second stitch, and the third stitch on one needle bed, and the first stitch on the other needle bed; step β of racking the needle bed, interchanging positions in the knitting width direction of the first stitch and the second stitch, and knitting a second stitch row including a fourth stitch, a fifth stitch, and a sixth stitch following in respective wale directions of the first stitch, the second stitch, and the third stitch; step γ of racking the needle bed in a direction opposite from the step β to return a left and right position relationship of the first stitch and the second stitch to a state identical with the step α; and step δ of knitting a third stitch row following in a wale direction of the second stitch row, fixing a position relationship of cross-over yarns formed between the first stitch and the second stitch, between the second stitch and the third stitch, between the fourth stitch and the fifth stitch, and between the fifth stitch and the sixth stitch to prevent unraveling of the knitting yarn at the yarn-in portion or the yarn-out portion. step α of knitting a first stitch row including a first stitch, a second stitch, and a third stitch continuing in a knitting width direction so as to satisfying requirement or, arranging the first stitch and the third stitch of the first stitch, the second stitch, and the third stitch on one needle bed and the second stitch on the other needle bed, arranging the second stitch and the third stitch of the first stitch, the second stitch, and the third stitch on one needle bed, and the first stitch on the other needle bed; arranging the first stitch and the third stitch of the first stitch, the second stitch, and the third stitch on one needle bed and the second stitch on the other needle bed, arranging the second stitch and the third stitch of the first stitch, the second stitch, and the third stitch on one needle bed, and the first stitch on the other needle bed; step β of racking the needle bed, interchanging positions in the knitting width direction of the first stitch and the second stitch, and knitting a second stitch row including a fourth stitch, a fifth stitch, and a sixth stitch following in respective wale directions of the first stitch, the second stitch, and the third stitch; step γ of racking the needle bed in a direction opposite from the step β to return a left and right position relationship of the first stitch and the second stitch to a state identical with the step α; and step δ of knitting a third stitch row following in a wale direction of the second stitch row, fixing a position relationship of cross-over yarns formed between the first stitch and the second stitch, between the second stitch and the third stitch, between the fourth stitch and the fifth stitch, and between the fifth stitch and the sixth stitch to prevent unraveling of the knitting yarn at the yarn-in portion or the yarn-out portion.