The precise data on the crystal and magnetic structures of SrRuO 3 were obtained by neutron diffraction. The ferromagnetically ordered Ru moment amounts to μ Ru =1.63±0.06μ B at T=10K. This value agrees well with the results of recent electronic structure calculations, which predicted the possibility of band ferromagnetism in SrRuO 3 with the reduced ordered moment. The crystal structure of SrRuO 3 remains practically invariable in the temperature range of 1.5–290K. We have also found that the “Invar effect” in SrRuO 3 (zero thermal expansion coefficient) is stipulated entirely by freezing of the mutual rotations/tilts of the oxygen octahedra below the phase transition into the ferromagnetic phase.