An apparatus for manufacturing a liquid crystal display panel, using a flexible substrate under atmospheric pressure. The apparatus includes a transferring unit for transferring a first substrate in a first direction so as to make the first substrate pass an attaching position for attaching the first substrate to a second substrate; and an attaching unit for attaching the first and second substrates passing the attaching position, wherein the attaching unit includes first and second rotating members respectively connected on one side and the other side of the second substrate so as to provide tension to the second substrate, wherein the first rotating member attaches the first and second substrates passing the attaching position.