From our current results of (Nd1-xCax)2Ir2O7, the internal field at 1.5 K increases with increasing the hole doping, the relaxation rate at 50 K increases with increasing the external field and shows a peak ~2.5 T at 15 K. The spin fluctuation shows the Redfield-like behavior at 1.5 K. In 3.6 T with x=0, a peak in the relaxation rate was observed ~50 K. Even in the case of x=0.07 in which only the ordering of Nd moments are expected below 1 K, we can still see a clear peak ~15 K. Those means Nd and/or Ir have low-lying spin fluctuations. We cannot catch up any fixed scheme to discuss it due to fewer data points. We would like to suggest more measurements in (Nd1-xCax)2Ir2O7 (x=0 at 5 K, 10 K, 25 K, 35 K, 100 K) and other Ca-doped samples (x=0.05, 0.07, 0.10, 0.20) to see a whole view of low-lying spin fluctuations and discuss the 4f-5d exchange interaction by measuring Y2Ir2O7.