A plant which expresses a large amount of ubiquinone-10 and a method for producing ubiquinone-10 using the plant are provided. A dietary supplement, a food and a food additive which contains ubiquinone-10 produced by the plant or the method are provided. The plant is produced by transformation using an expression cassette in which a decaprenyl diphosphate synthase gene is operatively linked with a mitochondrial targeting sequence.