The present invention provides a method for suppressing generation of hydrogen gas at the time when an ion concentration gradient is generated by a temperature responsive electrolyte. An electrolytic solution contains a temperature responsive electrolyte and an oxidation-reduction active species. The temperature responsive electrolyte is an electrolyte whose pKa varies according to the temperature. A power generating device 100 performs power generation by using the electrolytic solution. The power generating device 100 includes a positive electrode 3, a negative electrode 4, a heating mechanism 6, and a cooling mechanism 5. The positive electrode 3 and the negative electrode 4 are immersed in the electrolytic solution. The heating mechanism 6 heats the electrolytic solution that is present in the vicinity of one of the positive electrode 3 and the negative electrode 4. The cooling mechanism 5 cools the electrolytic solution that is present in the vicinity of the other one of the positive electrode 3 and the negative electrode 4.