The present invention provides a novel electrolyte solution capable of providing electrochemical devices whose internal resistance is less likely to increase even after repeated charge and discharge and whose cycle capacity retention ratio is high. The electrolyte solution of the present invention contains a solvent, an electrolyte salt, and at least one selected from the group consisting of compounds represented by R 11 X 11 -SO 3 M 11 and compounds represented by R 21 R 22 N-SO 3 M 21 in an amount of 0.001 to 10 mass% relative to the solvent.
