With respect to reduced coenzyme Q10, there has been no report about the presence of crystal polymorphism, and it has been considered that a conventionally obtained crystal form is only one form. The present invention relates to a reduced coenzyme Q10 crystal having an endothermic peak indicating melting at 54 ± 2°C during temperature rise at a rate of 5°C/min by differential scanning calorimetry (DSC), and/or to a reduced coenzyme Q10 crystal showing characteristic peaks at diffraction angles (2¸ ± 0.2°) of 11.5°, 18.2°, 19.3°, 22.3°, 23.0° and 33.3° by powder X-ray (Cu-K±) diffraction. The crystal form is a novel reduced coenzyme Q10 crystal which has a higher melting point and a lower solubility in a solvent, and is more excellent in stability than the conventionally known reduced coenzyme Q10 crystal.
