Filamin A-interacting protein (FILIP) is a filamin A binding protein and is involved in the radial migration of neurons via the acceleration of filamin A degradation. FILIP contributed to the characteristic morphology of the dendritic spine of neurons of the adult piriform cortex, where it is localized in the dendrites and spines. Several lines of evidence indicate that inhibition nonmuscle myosin IIb function in the neurons leads to the elongation of the spine. We found that FILIP bound to the head domain of nonmuscle myosin IIb, where the actin-binding domain is localized, and blocked its binding to actin fibers. Since FILIP has no apparent functional domains that cause alteration in the intracellular distribution of nonmuscle myosin IIb, we further tried to ascertain the region of FILIP responsible for the intracellular localization of nonmuscle myosin IIb. We observed that one of the chaperone proteins bound to C-terminal of FILIP was partially responsible for the alteration of intracellular localization of nonmuscle myosin IIb. Further investigation revealed that the inhibitor of this chaperone protein blocked the functioning of FILIP, thereby preventing the action of FILIP on neuronal spine morphology.