Using an ordered Fe72Pt28 Invar alloy single-crystal, spin modulations due to the local lattice distortions in the premartensitic embryos were studied by neutron scattering. Magnetic diffuse scattering caused by the modulations of spin structure was found around the (1 0 0) and (1 1 0) super-lattice points. The diffuse scattering intensity caused by the spin modulations is far stronger than that due to the lattice displacement of the localized spins. The spin modulations extend to wider space than the cluster sizes with the lattice distortion. Relations are discussed between the spin modulations and the various anomalous magnetic behaviors reported by previous authors as common properties of the Invar alloys.