The molecular orientation and dynamics of 4-hydroxy-2,2,6,6-tetramethyl-1-piperidinyloxyl (TEMPOL) radicals in one-dimensional (1D) nanochannels of the crystal of tris(o-phenylenedioxy)cyclotriphosphazene (TPP) were examined using electron spin resonance (ESR) measurements. TEMPOL radicals in the TPP nanochannels performed rotational diffusion motion not around the principal y axis of the g-tensor, as observed in most cases of TEMPO derivatives, but approximately around the principal z axis with much larger activation energy.