An example is given of a relativistic wave equation of a system of $N$ particles with interaction potential containing only $N$ -particle forces. The equation is formulated in the variables $t$ , $g_1$ , $g_2,\dots$ , where $g_i$ are the three-dimensional parts of the four-velocities, and the equation is a direct generalization of the Sehrödinger equation in the $p$ -representation. The transformations of the wave function allowed by the equation form a group that is isomorphic to the Poincare group and, when the interaction is switched off, they form a group that is isomorphic to the direct product of Poincare groups. An analog of the configuration $x$ -space is constructed and it is shown that the equation is consistent with classical relativistic mechanics of many bodies.