Since the discovery of the first icosahedral quasicrystal (QC) by Shechtman et al., their detailed atomic structures eluded researchers for many years until the recent structure solution of the binary icosahedral Cd5.7Yb quasicrystal. As far as the magnetism of moment bearing QCs, no long-range magnetic order but only spin-glass like freezing has been observed to date, and hence, the spin-glass behavior has been regarded even as an intrinsic property of magnetic clusters with icosahedral symmetry. However, it was recently shown that their crystalline counterparts, i.e., approximant crystals (ACs), exhibit magnetic transitions. Recently we reported observations of ferromagnetic (FM) transitions in Au-based approximants Au-SM-RE (SM=Si,Ge and RE=Rare Earth), which are ternary alloys related to the Cd5.7Yb quasicrystal, and are composed of so-called Tsai-type clusters containing RE12 icosahedra. Our present aim is to perform the first detailed investigations of magnetic structures on these quasicrystal approximants by single crystal neutron diffraction, in order to understand the relation between the structural variations and the magnetic properties.