A sewing machine includes a bed, a needle plate, a needle bar, a needle bar swing mechanism, an optical detecting portion, and a control portion. The optical detecting portion is configured to optically detect a cord pressed by a presser foot, and to output data representing the cord. The control portion is configured to calculate a width of the cord based on the data output by the optical detecting portion, calculate a swing width of the needle bar based on the width of the cord, and cause the needle bar swing mechanism to swing the needle bar with the swing width.