Abstract: Modulation of pluripotent stem cell differentiation by several environmental factors, such as physical stimulation, is important theme in tissue engineering. In this study, we report the effects of extremely low frequency magnetic fields (ELF-MFs) exposure (1 mT or 10 mT, 50 Hz, sinusoidal) on the neuronal differentiation process of P19 embryonal carcinoma cells (P19 cells). Here, during induction of differentiation, the ELF-MFs exposed to embryoid bodies (EBs). After neuronal differentiation, the effects of ELF-MFs were evaluated by morphological analysis, immunochemical analysis (MAP2, GFAP), and the developmental neuronal network activities recorded by the micro-electrode arrays (MEAs). As a result, the percentage of MAP2 positive cells and the spike frequencies were increased by 10 mT ELF-MF, and then the percentage of GFAP positive cells were reduced. However, these effects were not seen in 1 mT exposed cells. Therefore, these results suggested that the intensity of a magnetic field was important for affecting a characteristic of neuronal differentiation and a functional neuronal network property.