An apparatus for attaching substrates is provided with a buffering member between an upper chamber and a lower chamber. The buffering member reduces a load applied to a lifting device during vacuum exhaustion of a sealing space between the chambers. Therefore, it is possible to reduce a force applied to a lifting screw and a frame supporting a chamber, thereby extending the lifetime of the substrate attaching apparatus and component replacement. Also, it is possible to increase a lower chamber supporting force of a lifting part by coupling the lifting part to an external frame with a fixing device. As the result, the lower chamber is stably fixed and thus it is possible to reduce failures in a substrate attaching process.