To provide a composition that has excellent ability to lower pour point and cloud point, which ability is not obtained by conventional and general biodiesel fuel (BDF) and a BDF modifier.

The composition is obtained by conducting a hydrogen peroxide process on biodiesel fuel without using a special device, such as an ozone gas generator. Fuel consumption in the cases below is improved by using the composition. (1) Solo use or combined use for a diesel engine (combined use of the composition with petroleum-based gas oil or the conventional and general BDF), (2) combined use of the composition with gasoline for a gasoline engine, and (3) combined use of the composition with heavy oil for a heavy oil boiler.