  We derive the simplest traversable wormhole solutions in $n$-dimensional
general relativity, assuming static and spherically symmetric spacetime with a
ghost scalar field. This is the generalization of the Ellis solution (or the
so-called Morris-Thorne's traversable wormhole) into a higher-dimension. We
also study their stability using linear perturbation analysis. We obtain the
master equation for the perturbed gauge-invariant variable and search their
eigenvalues. Our analysis shows that all higher-dimensional wormholes have an
unstable mode against the perturbations with which the throat radius is
changed. The instability is consistent with the earlier numerical analysis in
four-dimensional solution.
