The present invention aims to provide an electrolyte composition from which an electrolyte film having a higher battery performance than typical electrolyte films is obtained. The present invention provides an electrolyte composition containing an alkali metal salt. The composition further contains a photocurable and/or thermosetting monomer; and a salt dissociating agent. A content ratio of the alkali metal salt is 50% by mass or more relative to 100% by mass of the total amount of the alkali metal salt, the photocurable and/or thermosetting monomer, and the salt dissociating agent.