An impedance matching device includes a tapered strip line and a plurality of strip lines. The tapered strip line extends in a first direction on a substrate and has a width in a second direction perpendicular to the first direction. The tapered strip line includes first to n-th segments having identical lengths and different widths, wherein the ‘n’ is a natural number of two or more. The plurality of strip lines are connected to the n-th segment such that an input signal received through the first segment is split.