Electron spin resonance (ESR) spectra of Nd0.7(Sr0.3-xCax)MnO3, powders (0 ≤ x ≤ 0.3) have been measured over the range of temperature between 110 and 290 K. While for x = 0.2, 0.25 and 0.3 only one absorption line (Line I), corresponding to a g-value around 2, was observed while for x = 0 and 0.1 an additional line (Line II) was observed below the magnetic transition temperature. Based on the temperature dependent g-values and AH, we have assigned the ESR signal of Line I to the Mn4+ -ions, while that of Line II to the ferromagnetic resonance due to the ferromagnetic coupling between Mn4+ and Mn3+.