A foldable brush for a cosmetic container includes a first brush body having a receiving hole, and a second brush body inserted into the receiving hole of the first brush body, wherein the first brush body includes a first brush including a lot of hair as a cosmetic brush; a first brush support for fixing the first brush and maintaining a fixing state of the first brush such that the first brush does not come off the first brush support; a guide body having a semi-cylindrical shape and a receiving hole, and connected to the first brush support; guide holes formed in both side surfaces of the guide body and having an L-shape; and a temporary fixing stopper formed in a lower end portion of the guide body and having a protrusion shape, and wherein the second brush body includes a second brush including a lot of hair as a cosmetic brush; a second brush support for fixing the second brush and maintaining a fixing state of the second brush such that the second brush does not come off the second brush support; a supporting body having a cylindrical shape, one side connected to the second brush support and an opposite side having a hemispherical shape; sliding hinge pins formed in both side surfaces of the supporting body and coupled to the guide holes of the first brush body such that a rotation of the supporting body is supported; and temporary fixing grooves formed in upper and lower portions of the supporting body, respectively and coupled to a temporary fixing stopper of the first brush body to allow the second brush to be maintained in a folded or unfolded state.