The self-assembly of gold nanorods (AuNRs) derivatized with photoisomerizable spiropyran ligands was investigated. Under UV irradiation, the AuNRs that were functionalized on the surface by spiropyran with a dithiolane formed end-to-end assemblies accompanied with isomerization of the spiropyran moiety, simultaneously showing a red-shift of the longitudinal plasmon band and the increase in absorbance resulted from the merocyanine form. The networked structure of AuNRs was ultimately built "on demand" by UV irradiation.