C. Wieczerkowski Construction of the hierarchical $\phi^4$-trajectory (120K, LATeX 2e) ABSTRACT. We study the invariant unstable manifold of the trivial renormalization group fixed point tangent to the $\phi^4$-vertex in the hierarchical approximation. We parametrize it by a running coupling with linear $\beta$-function. The manifold is studied as a fixed point of the renormalization group composed with a flow of a running coupling. We present a rigorous construction of it by means of a contraction mapping.