An apparatus for producing a solid fuel which may be made by a method involving mixing porous coal with a mixed oil containing heavy oil and solvent oil to prepare a raw material slurry; heating the raw material slurry to promote dehydration of the porous coal while impregnating the mixed oil into pores of the porous coal to obtain a dehydrated slurry; separating the resulting upgraded porous coal and mixed oil from the dehydrated slurry; drying the separated upgraded porous coal with carrier gas, and subsequently condensing vaporized mixed oil in the carrier gas by cooling, while capturing the porous coal in the carrier gas by atomization of the condensed mixed oil, thereby recovering the mixed oil; and returning the mixed oil separated and recovered in the separating to the mixing, further involving supplying the mixed oil recovered in the final drying to the separating.