We investigated the magnetoresistive property of a micrometer-scale Ni wire with a uniaxial magnetic anisotropy induced by the formation of a heterojunction between a Ni layer and a single-crystal lithium niobate (LiNbO3) substrate. We revealed that the domain structure can be controlled by adjusting the wire alignment and that its magnetoresistance (MR) is dependent on the magnetic domain structure as well as the reversal process. The introduction of a heterojunction is a crucial method of controlling the magnetic domain structure owing to the additional generation of the magnetic anisotropy. This control of the magnetic domain structure is very useful for investigating the fundamental physical mechanism and producing artificial multiferroic functional materials and devices. The relatively large MR response observed in transport measurements alludes to the possibility that the spin-dependent scattering mechanism occurs in the domain and domain wall.