In a steering column provided with a knee airbag device to a vehicle, an airbag module, which is integrally provided on an airbag door formed separately from a column lower cover, is fitted to a column tube after a steering column body is assembled, and before a steering lock is fitted to the column tube. Then, after the airbag module is fitted to the column tube, a steering column sub-assembly, which is formed by fitting at least the steering lock to the column tube, is fitted to an instrument panel provided in a vehicle at a predetermined position. After the steering column sub-assembly is fitted to the instrument panel, the column lower cover and a column upper cover, which cover a rear end portion of the steering column, are fitted to the steering column.