We performed fMRI measurements in normal children to clarify which cortical areas are commonly involved in the mirror system (MS) and mentalizing, which areas are specific for mentalizing, and whether children have the same neural networks for MS and mentalizing as adults. Normal children had the same neural networks for the MS and mentalizing as adults. Common activations were found in the superior temporal sulcus and the fusiform gyri, whereas mentalizing specific activation was found in the medial prefrontal, temporal pole and the inferior parietal cortices. We suggest that mentalizing might evolve from a capacity to detect the motion of agents and to infer intentions. Further, mentalizing might require self-perspectives.