A hydrocarbon oil for use as a raw material for hydrogen production in a hydrogen production system employing a burner as a heat source, the hydrocarbon oil having a flash point of 40 DEG C or higher,sulfur content of 0.3 mass ppm or lower, molar ratio of hydrogen element to carbon element in the hydrocarbon oil (H/C) of 2.00 or higher, aromatic content (Aroma) of 10 vol.% or lower, naphthene content of 40 vol.% or lower, 95-vol.% running temperature of 250 DEG C or lower, and steam reforming index of 20 or higher.