To provide a process for producing a hydrotreated oil in good productivity without encountering the problem of the formation of hot spots in the catalyst layer and the solidification of the catalyst layer in the hydrotreatment of heavy hydrocarbon oil.

In a process for producing a hydrotreated oil by bringing a heavy hydrocarbon oil and a hydrogen gas into contact with the catalyst in a catalyst layer, a mixture prepared by combining a metal-supported inorganic oxide catalyst (A) carrying at least one metal selected among the metals of groups 6, 8, 9 and 10 with a zeolite catalyst (B) prepared by bringing a mineral acid solution having a pH of 1.5 or below or a metal salt aqueous solution of at least one member selected among the metals of groups 8, 9 and 10 downstream of the catalyst layer is used.