The present application relates to an apparatus for purifying cumene comprising: a first dividing wall type distillation column which takes in a stream from an alkylation reactor and comprises a first benzene output line and a benzene/cumene/polyisopropylbenzene stream output line; a second dividing wall type distillation column which takes in a stream from a transalkylation reactor and a benzene/cumene/polyisopropylbenzene stream, includes a transalkylation reactor stream input line, a benzene/cumene/polyisopropylbenzene stream input line, a second benzene output line, and a first polyisopropylbenzene stream output line; and a third distillation column which takes in a polyisopropylbenzene stream, includes a second polyisopropylbenzene output line, and a heavies output line.