A holder for a seamless control cord of a curtain for quickly fixing the seamless control cord or a bead chain is composed of a base seat, an outer cover and elastic members and fixed on a wall face by fixing members. The base seat and the outer cover are respectively formed with two perforations. Each perforation has a cord passage formed on the same axis. When holding the control cord, the seamless control cord is directly passed through the cord passage of the outer cover into the perforation and then passed through the cord passage of the base seat into the perforation. Then, the elastic members push the outer cover to misalign the two perforations so as to hold the control cord and fully fix the control cord. Under such circumstance, the control cord is prevented from swinging or a child cannot play the control cord.