PURPOSE: To make it possible that a vacuum distillation fraction can be used as a feed to a catalytic cracking apparatus by demetallizing a vacuum distillation fraction in a specified temperature range of a heavy fossil fuel to remove Ni and V.

CONSTITUTION: A heavy fossil fuel is vacuum-distilled to be fractionated into a fraction having an initial cut point of 427 to 566°C (800 to 1050°F) and a deep-cut vacuum gas oil having a final cut point of 579 to 704°C (1075 to 1300°F) and only the deep-cut vacuum gas oil is hydrogenated in the presence of an Mo-containing catalyst to demetallize 40 wt.% or more of Ni and V thereby producing a distillate having a V content of 15 ppm or less and an Ni content of 10 ppm or less suitable as a feed to a catalytic cracking apparatus.