The effects of unidirectional pulling forces on covalently bridged cysteamine between superparamagnetic particles and Ag nanoparticles (NPs) were studied with SERS spectroscopy. With an increase in the pulling force from 0 to 100 pN per magnetic particle, the nu(C-S)(Trans)/nu(C-S)(Gauche) intensity ratio was increased from 0.6 to 1.08, the Raman frequency of nu(C-S)(Trans) was shifted from 716 to 719 cm(-1), and the Raman bands associated with the amide groups were diminished. From these observations, it was concluded that the magnetic forces induced the extension of distance between the magnetic particle surface and the Ag NP surface and the rotational isomerization equilibrium of SC-CN was shifted from the gauche to the trans conformation with the longer molecular length.