Suppose that (M, g) is a complete and noncompact Riemannian mani-fold with Ricci curvature bounded below by ¡K · 0 and (N, g) is a complete Riemannian manifold with nonpositive sectional curvature. Let u : M x [0,∞) ! N be the solution of a heat equation for harmonic map with a bounded image. We estimate the energy density of u.