Abstract: A process for feed oil refining for production of lubricating oil, by using an equipment for lubricating oil production including a fulfural refining unit, a hydrotreating unit and a ketone dewaxing unit, all connected in series. In this process, operations associated with the switch of feed oil are conducted by carrying out the first to seventh step groups successively. Each step group is initiated when a given time has passed since the start of the previous step group, or when the value of a particular measurement item has reached a target value, or when the value of a particular measurement item has shown a change. First, in the first step group, the amount of feed oil supplied to each unit, etc. is adjusted and, in the second step group, the feed oil to the furfural refining unit is switched.