General guiding principles of introducing the pinning centers for the achievement of high current density are discussed in metallic superconducting composite wires. It is pointed out that, among various methods satisfying these guiding principles, the use of artificial pinning centers is more advantageous than other existing methods for the achievement of high current density. The present status on the development of the NbTi composite wires using artificial pinning centers are reviewed. The flux-pinning mechanisms of various types of artificial pinning centers are also discussed.
