We developed an experimental system to characterize the suppressive effect of extremely low‐frequency (ELF) electric fields (EFs) on the stress response. We assessed differences in the EF effects by age and gender. Control, EF‐alone, immobilization‐alone, and co‐treated groups were subjected to an EF (50 Hz, 10 kV/m). Co‐treated mice were exposed to the EF for 60 min, with immobilization during the latter half. Our results indicate that the suppressive effects of ELF EFs on the stress response in immobilized mice occur regardless of gender or age. As stress plays an important role in the onset and progression of various diseases, these findings may have broad implications for understanding the efficacy of EFs in animal, and perhaps human, health. Bioelectromagnetics. 2020;41:156–163. © 2019 Bioelectromagnetics Society.