We studied the adsorption of polystyrene nanospheres that have anionic charges on their surfaces from their aqueous dispersions onto the surfaces of cationic ultrathin polymer films quantitatively and kinetically by using a quartz crystal microbalance (QCM) and scanning electron microscopy(SEM). The polymer films were successively prepared by the alternate adsorption of poly(allylamine hydrochloride) (PAH) and poly(sodium 4-styrenesulfonate) (PSS) in the absence or presence of suitable NaCl concentrations onto the QCM substrate so that we could observe their formation process by its frequency shifts. We observed the specific adsorption of the nanospheres by means of electrostatic interaction onto the outermost PAH surface by QCM as well. The dependence of their adsorption amounts against the NaCl concentration in polymer precursor film preparation was a sigmoid curve, indicating that there is a critical charge on/in the film for their adsorption. SEM observations showed monolayer adsorption without three-dimensional aggregation. We also studied the effects of particle size on their adsorption behavior and the possibility of the multilayering of nanospheres. This research on adsorption behavior by electrostatic interaction will be applied to the adsorption system of not only polymeric nanospheres but also other inorganic nanoparticles.