This disclosure is directed to an X-ray security device having a main body, a conveyor, and a lead curtain. The main body has an opening. The conveyor passes through the opening and is disposed on a bottom of the opening. The lead curtain is hung on the main body and covers the opening, the lead curtain has a pair of outer modules and a central module, the pair of outer modules are arranged corresponding to two sides of a transport direction of the conveyor, and the central module is disposed between the outer modules. A lead equivalent thickness of each outer module is larger than a lead equivalent thickness of the central module, and a weight of the central module is less than a weight of each outer module.