Ionic liquids exhibit a stable liquid state even at low temperatures and have a good conductivity. The ionic liquids each contain an organic compound represented by the following formula (1) as a cation. ##STR00001## In the formula, R.sub.1 to R.sub.5 may be the same as or different from each other and each represents an H, a halogen, or a C.sub.1 to C.sub.10 alkyl group, cycloalkyl group, heterocyclic group, aryl group or alkoxyalkyl group; X and Y may be the same as or different from each other and each represents an N or a P; Z represents an S or an O.