  Let $K$ be an imaginary quadratic field where $p$ is inert. Let $E$ be an
elliptic curve defined over $K$ and suppose that $E$ has good supersingular
reduction at $p$. In this paper, we prove that the plus/minus Selmer group of
$E$ over the anticyclotomic $\mathbb{Z}_{p}$-extension of $K$ has no
non-trivial $\Lambda$-submodules of finite index under mild assumptions for
$E$. This is an analogous result to R. Greenberg and B. D. Kim for the
anticyclotomic $\mathbb{Z}_{p}$-extension essentially. By applying the results
of A. Agboola--B. Howard or A. Burungale--K. B\"uy\"ukboduk--A. Lei, we can
also construct examples satisfying the assumptions of our theorem.
