We consider a complete biharmonic submanifold ϕ:(M,g)→(N,h)ϕ:(M,g)→(N,h) in a Riemannian manifold with sectional curvature bounded from above by a non-negative constant cc. Assume that the mean curvature is bounded from below by √c√c. If (i) ∫M(|H|2−c)pdvg<∞∫M(∣∣H∣∣2−c)pdvg<∞, for some 0<p<∞0<p<∞, or (ii) the Ricci curvature of MM is bounded from below, then the mean curvature is √c√c. Furthermore, if MM is compact, then we obtain the same result without the assumption (i) or (ii). These are affirmative partial answers to Balmuş–Montaldo–Oniciuc conjecture.