Using the direct method, we prove the Hyers-Ulam stability of the orthogonally additive-quartic functional equation (0.1) $f(2x+y)+f(2x-y)=4f(x+y)+4f(x-y)+10f(x)+14f(-x)-3f(y)-3f(-y)$ for all $x$, $y$ with $x{perp}y$, in non-Archimedean Banach spaces. Here ${perp}$ is the orthogonality in the sense of R$ddot{a}$tz.