A method for manufacturing a knee airbag cushion includes (a) preparing a panel having first and second panel surface parts and a virtual central line interposed between the first and second panel surface parts and is configured such that a distance from the virtual central line to the first panel surface part is different from a distance from the virtual central line to the second panel surface part, (b) folding the first panel surface part, (c) connecting portions of the first and second panel surface parts to each other, (d) folding an area of the virtual central line in the folding direction, and (e) forming a third sewing line to connect the first panel surface part to the second panel surface part.