<p>An objective of the present invention is to provide methods of producing human collagen molecules that are easy to isolate and purify and that have a structure substantially equivalent to that of a natural collagen molecule, wherein host cells that are transduced with a collagen gene synthesize large amounts of human collagen protein derived from a gene introduced into a high exogenous gene expression vector. Another objective of the present invention is to provide collagen molecules produced by the production methods. The present inventors discovered that a large amount of human collagen hardly contaminated with host cell-derived collagen could be produced, by selecting from various mammalian cells a host cell that has low collagen expression and introducing a collagen gene construct into a vector capable of high exogenous gene expression.</p>
