Magnetization curve measurement in the spin-ordered state of an enhanced nuclear magnet PrCu 6 has been carried out. Hysteresis due to a ferromagnetic domain structure is observed. The hysteresis appears when the magnetic field is applied along the c-axis, but not along the b-axis. This strongly anisotropic behavior suggests that a possible spin structure in the ordered state is a canted ferromagnet: ferromagnetically aligned along the c-axis with magnetic domains but antiferromagnetically along b-axis.