A process for production of a lubricating base oil whereby a lubricating base oil is obtained by a first step in which a stock oil containing normal paraffins of C20 or more is subjected to isomerization reaction so that the content of the normal paraffins of C20 or more is 6-20 wt % based on the total weight of hydrocarbons of C20 or more in the obtained reaction product, a second step in which a lube-oil fraction containing hydrocarbons of C20 or more is separated from the reaction product of the first step, and a third step in which the lube-oil fraction obtained in the second step is separated into a dewaxed oil and a wax by a solvent dewaxing treatment.