In this article, we establish an ℓ 2 decoupling inequality for the hypersurface, where m ≥ 4 is an even number, associated with the decomposition adapted to finite type hypersurfaces from our previous work [18]. The key ingredients of the proof include an ℓ 2 decoupling inequality for the hypersurfaces (ξ 1 , ..., ξ n−1 , φ 1 (ξ 1 )+...+φs(ξs)+ξ m s+1 +...+ξ m n−1 ) : (ξ 1 , ..., ξ n−1 ) ∈ [0, 1] n−1 , 0 ≤ s ≤ n − 1, with φ 1 , ..., φs being non-degenerate. As an application, we generalize the Schrödinger maximal estimates in [19] to higher dimensions.