A cluster device having a dual structure includes: a substrate storage containing a plurality of substrates, the substrate storage having an ATM robot that moves said substrates; a first cluster including a first transfer chamber having a vacuum robot, a plurality of first process chambers connected to the first transfer chamber, and a first load lock chamber connected to both the substrate storage and the first transfer chamber, a second cluster including a second transfer chamber under the first transfer chamber, a plurality of second process chambers connected to the second transfer chamber, each of the plurality of second process chambers positioned between the two first process chambers, and a second load lock chamber connected to both the substrate storage and the second transfer chamber.