An apparatus for treating a substrate includes an index module and a treatment module that treats the substrate. The index module includes a load port on which a carrier having a plurality of substrates received therein is loaded and a transfer frame that is disposed between the treatment module and the load port and that transfers the substrate between the carrier loaded on the load port and the treatment module. The treatment module includes one or more process chambers and a transfer chamber that transfers the substrate to the process chambers. The transfer chamber includes a housing having a transfer space in which the substrate is transferred, a transfer robot that is disposed in the housing and that transfers the substrate between the process chambers, and an electrostatic pad that is provided in the transfer space and that electro-statically attracts particles in the housing.