Our goal in this paper is to investigate ergodicity of the white-forced wave equation on the whole line. Under the assumption that sufficiently many directions of the phase space are stochastically forced, we prove the uniqueness of stationary measure and polynomial mixing in the dual-Lipschitz metric. The difficulties in our proof are twofold. On the one hand, compared to stochastic parabolic equation, stochastic wave equation is lack of smoothing effect and strongly dissipative mechanism. On the other hand, the whole line leads to the lack of compactness compared to bounded domain. In order to overcome the above difficulties, our proof is based on a new criterion for polynomial mixing established in [20], a new weight type Foiaş-Prodi estimate of wave equation on the whole line and weight energy estimates for stochastic wave equation.