PURPOSE: To obtain a liquid product in high yield by reduced formation of L, H2 and coke, by catalytically cracking heavy hydrocarbon oil including Ni, V or the like in the presence of a specific catalyst having a specific SiO2/Al2-O3 molar ratio, a specific unit lattice dimension and a specific molar ratio of Al in the zeolite skeletal.

CONSTITUTION: In the catalytic cracking of heavy hydrocarbon oil including one or both of Ni and V, smooth catalytic cracking of the heavy hydrocarbon oil including these metals contaminating the cracking catalyst can be done by using the catalyst comprising crystalline aluminosilicate salt which causes the results such as 5.5 to 6.9 SiO2/Al2O3 molar ratio in bulk according to the chemical analysis, 24.34 to 24.46 unit lattice dimension, 0.2 to 0.4 molar ratio of the Al in a zeolite skeletal to the total Al calculated according to the equation I (a0 is the unit lattice dimension in nm; NAl is the number of Al atoms per the unit lattice), formula II and formula III and exhibiting Y type of the major X-ray diffraction pattern of the zeolite and the inorganic oxide matrix, in the case where the catalyst is contaminated with one or both of 3,000 to 13,000ppm of nickel and vanadium.