PURPOSE: To efficiently utilize high sulfur-containing crude oil or oil having a high sulfur content for a pretreatment of crude oil.

CONSTITUTION: This new storing method of crude oil comprises passing the crude oil through a desalting apparatus and storing the resultant crude oil in a tank of a hydrogen atmosphere. At the same time, cracking of the crude oil is accelerated by previously mixing high sulfur-containing crude oil into the crude oil or storing oil having a high sulfur content in the tank together with the treated crude oil. Resultant cracked oil is separated by storing in an atmospheric distilling tower, etc.