A decision is made as to whether a fabric to be knitted is tubular or flat, and density is corrected such that knitting-start density is smaller and knitting-end density is larger for a tubular fabric. Knitting-start density is larger and knitting-end density is smaller for a flat fabric. A variable density section is provided between the end part and the central part of the fabric thus correcting the density gradually. Stitches at the end part of the fabric are prevented from becoming uneven as compared with the stitches in the central part without requiring additional hardware.