Methacrylate (MA) monomers were graft copolymerized on an isotactic polypropylene (PP) film surface by the UV-irradiation method. Tethered poly(methyl methacrylate) (PMMA) and poly(butyl methaerylate) (PBMA) chains were spin-labeled to study molecular motion of the PMMA and PBMA chains in the solvent of toluene by electron spin resonance (ESR). Pinacol radicals from benzophenone (BP) as a photoinitiator, adsorbed on the PP film surface, behaved just like a dormant bonded to propagating radicals on "living" radical graft copolymerization. The chains of BP-terminated polymethaerylate (PMA) grafted to the PP were extended by sequential activation of the dormant chain ends in the presence of additional MA monomers. On the other hand, gel and sol phases of the PMA chains were produced on the PP surface. Molecular mobility of the PMA chains was strongly affected by physical structures of both PMA and PP. ESR spectra of the chains in the toluene matrices were composed of two spectra arising from two kinds of spin-labels, A- and B-labels. They were a mobile label (A) in isolated single-chain globules and smaller pinned micelles and a rigid label (B) in larger pinned micelles and the gel phase on the PP surface. The fractional amount of the mobile labels decreases with increases in grafting amount and the degree of orientation of the PP chains. It was also found that the PMMA chains were more mobile than the PBMA chains in the isolated single-chain globules on the PP surface despite the higher glass transition temperature of the PMMA in the bulk than that of PBMA. The factors for the determination of the molecular mobility of the tethered chains were discussed and related to the conformational structure.