NOVELTY - An ionic liquid contains an organic compound (1) as a cationic component.    USE - As electrolyte liquid for electrical storage device, lithium secondary battery, electrical double layer capacitor, dye sensitized solar cell, fuel cell, and reaction solvent (all claimed).    ADVANTAGE - The ionic liquid has low viscosity, favorable electroconductivity and excellent electrochemical stability, and exhibits stable liquid state in wide temperature range.    DETAILED DESCRIPTION - An ionic liquid contains an organic compound of formula (1) as a cationic component.    R1-R9=H, 1-30C alkyl having linear or side chain, 2-30C alkenyl having linear or side chain with 1 or more double bond, 2-30C alkynyl having linear or side chain with 1 or more triple bond, saturated or partially or completely unsaturated cycloalkyl, aryl, or heterocyclic group, and H contained in substituents R1-R9 is partially or completely substituted by halogen atom, or by CN and NO2 group partially, and arbitrary substituents R1-R9 optionally forms cyclic structure, and carbon atom contained in the substituents R1-R9 is substituted by atom and/or atom group chosen from -O-, -C(O)-, -C(O)O-, -S-, -S(O)-, -SO2-, -SO3-, -N=, -N=N-, -NH-, -NR'-, -N(R')2-, -PR'-, -P(O)R'-, -P(O)R'-O-, -O-P(O)R'-O- and -P(R')2=N-;    R'=1-10C alkyl having linear or side chain, alkyl substituted partially or completely with F atom, saturated or partially or completely unsaturated cycloalkyl, (un)substituted phenyl, or (un)substituted heterocyclic;    X=S, O or C atom;and    dotted line=conjugation structure.    When X is C atom, only R8 and R9 exists. When X is C atom, X, R1, R8 and R9 optionally forms saturated or partially or completely unsaturated cyclic structure.    INDEPENDENT CLAIMS are included for:    (1) electrical storage device;    (2) lithium secondary battery;    (3) electrical double layer capacitor;    (4) dye sensitized solar cell;    (5) fuel cell;    (6) reaction solvent; and    (7) manufacture of ionic liquid, which involves alkylating organic compound of formula (2).