Molecular nature of the <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msub><mml:mi>a</mml:mi><mml:mn>1</mml:mn></mml:msub><mml:mo stretchy="false">(</mml:mo><mml:mn>1260</mml:mn><mml:mo stretchy="false">)</mml:mo></mml:math> axial-vector meson

We investigate $\ensuremath{\pi}\ensuremath{\rho}$ scattering based on the coupled-channel formalism with and $K{\overline{K}}^{*}$ ($\overline{K}{K}^{*}$) channels included. construct kernel amplitudes by using meson-exchange model compute coupled integral equation for scattering. By performing partial-wave expansion, we show explicitly that ${a}_{1}(1260)$ meson is dynamically generated formalism. The ${a}_{1}$ only appears including channel. obtain pole position of as $\sqrt{{s}_{R}}=(1170.7\ensuremath{-}i173.0)\text{ }\text{ }\mathrm{MeV}$. conclude can be interpreted a kaon vector molecular state.