One of the pyrochlore systems, Nd2Ru2O7, shows unique magnetic properties and can be a candidate of the electrocatalyst material for industrial applications. This system shows magnetic anomalies around 1.8 K, 21 K, and 146 K. The anomaly at 21 K is suggested to be coming from the impurity component of Nd3RuO7 and is still debatable. To investigate the effects of impurities on the magnetic properties of this sample, we synthesized some samples (labelled as Sample-I and II) using the solid-state reaction method with different heat treatment conditions and measured the magnetic susceptibility. We found that low sintering temperatures generated impurity phases of raw materials and Nd3RuO7. We also confirmed that those impurity phases were able to be reduced by optimizing heat treatment conditions. The optimum temperature for the sintering process should not be higher than 1000°C. The higher sintering temperatures yield more Nd3RuO7 impurity phases. Magnetic susceptibility measurements showed that samples with Nd3RuO7 impurity phases exhibited a peak around 21 K in the zero field-cooled condition accompanied by a broad peak around 12 K in the field-cooled condition indicating the appearance of Nd3RuO7.