We report a case of plexiform schwannoma located in the flexor muscles of the forearm in the absence of other signs of neurofibromatosis or schwannomatosis. Magnetic resonance examination revealed a multinodular irregular inhomogeneous mass. Some nodules displayed a peripheral, high intensity rim and a central low intensity (target sign) on T2-weighted images. Pre-operative diagnosis of the rare plexiform schwannoma may be possible with careful imaging examination for the target sign.