An electrolyte composition comprising a compound represented by the following general formula (1): wherein R represents a substituent containing a —(CR1R2—CR3R4—O)n— bond (in which R1 to R4 are independently a hydrogen atom or an alkyl group, n being an integer of 2 to 20); Q represents an atomic group forming an aromatic cation having a 5- or 6-membered ring structure with a nitrogen atom, which may have a substituent; and X− represents an anion. A photoelectric conversion device comprising the electrolyte composition and a photo-electrochemical cell composed thereof are also provided.