An electrochemical device includes a case, a nonaqueous electrolyte filled in the case and containing a room temperature molten salt in an amount of 1 to 50 vol %, a first electrode housed in the case, and a second electrode housed in the case and containing a substance having a lamellar crystal structure. The room temperature molten salt contains a cation represented by formula (1) or formula (2) given below. R1 includes a carbonic acid ester group. Each of R2 and R3 denotes a substituent having an acyclic structure and having 4 or less carbon atoms, or R2 and R3 are combined to denote a substituent having a cyclic structure and having 4 or 5 carbon atoms. R4 includes a carbonic acid ester group, R5 has an acyclic structure and has 4 or less carbon atoms, and R6 denotes a hydrogen atom or a methyl group.