The present invention is related to a method of subjecting a feed oil to a refining process. This method includes a fractional distillation step 1 in which a feed oil is separated into a distillate oil M1 and a bottom oil M2 by a distillation process, a separation step in which the bottom oil is separated into a bottom light oil and a residue, and a hydrorefining step 3 in which the obtained distillate oil M1 and the bottom oil M2 are subjected to hydrorefining in the presence of hydrogen and a catalyst. In the hydrorefining step 3, the bottom light oil (deasphalted oil M3) is passed through a first catalyst layer 12 of a hydrorefining unit providing a plurality of catalyst layers 12, 13, and 13 filled with a hydrorefining catalyst, and a mixed oil comprising the distillate oil M1 and the bottom light oil (deasphalted oil M3) is passed through a downstream catalyst layer 13 and subject to a hydrogenation process.