We have fabricated n-UCT SrRuO3/SrTiO3 superlattices, [SrTiO3 5-UCT/SrRuO3 n-UCT](m) (n = 1 similar to 20), where UCT is a unit-cell thickness, on SrTiO3(001) substrates to study a low-dimensional structural effect on the magnetic properties of SrRuO3. We measured temperature-dependent and field-dependent magnetization. The ferromagnetic transition temperature decreased with decreasing n, and the transition vanished for n = 1. A strong anisotropy of magnetization with an easy axis perpendicular to the film plane was observed for all the samples, as seen in SrRuO3 thin films on SrTiO3(001) substrate. The in-plane magnetization was extremely suppressed as n decreased. For 3-UCT superlattice, the in-plane magnetization became 1/10 of the out of plane magnetization at T = 5 K and H = 1 T. The role of low-dimensionality between SrRuO3 and SrTiO3 on magnetism of SrRuO3 is discussed.