PURPOSE: To obtain a high purity coenzyme Q having excellent remedying effect to various diseases in the living body, easily in high recovery, by extracting crude coenzyme Q with a nitrile compound, adjusting the concentration of solute in the extract, and crystallizing at a specific temperature.

CONSTITUTION: Purification of crude coenzyme Q by extracting with nitrile followed by crystallizing. The extraction is carried out by using a nitrile compound such as aliphatic, aromatic or heterocyclic nitriles, e.g. acetonitrile, benzonitrile, cyanopyridine, etc. at 30W50°C. The amount of the nitrile is 20W50 times volume of the crude coenzyme Q. The concentration of solute in the extract is adjusted to 0.2W 1.2%, and crystallized at +5W-10°C to obtain the objective high purity coenzyme Q. The recrystallization is repeated if necessary.