The invention relates to a slide rail fixing device. The slide rail fixing device (100) according to the invention couples a supporting bar (110), mounted on an inner wall of a main body (10), and a slide rail (30), mounted on a side surface or a bottom surface of a drawer body (20), and is characterized in that the slide rail fixing device (100) comprises: a fixing upper plate (101) positioned atan upper part of the supporting bar (110) and fixed to the slide rail (30); a fixing lower plate (103) positioned at a lower part of the supporting bar (110); a connecting plate (102) for connectingthe fixing upper plate (101) and the fixing lower plate (103); and an extended plate (104) formed to extend from the fixing lower plate (103) so as to face the fixing upper plate (101). According to the invention, a gap (GAP) is formed between the slide rail fixing device and a vertical supporting bar such that the movement, of the slide rail fixing device, generated when the drawer body is withdrawn or inserted, can be offset. Therefore, the concentration of torsional stress, caused by the withdrawal or the insertion of the drawer body, is prevented such that the deformation of the slide railfixing device or the separation thereof from the supporting bar can be prevented.