Disclosed is a method for producing a cell population into which a desired gene is introduced, which is characterized by comprising the following steps (1) and (2): (1) culturing a cell population containing a T-cell and/or a progenitor cell of a T-cell in a vessel containing fibronectin or a fragment thereof and a CD3 ligand； and (2) adding a vector carrying the desired gene to the vessel of the step (1). By carrying out both the steps (1) and (2) in the same vessel, the gene transfer can be achieved with high efficiency.
