The present invention relates to a finishing panel fixing device, and more particularly, to a finishing panel fixing device that fixes a finishing panel so that the finishing panel can be stably fixed when installing the finishing panel for finishing an indoor or outdoor wall surface or a floor. The finishing panel fixing device according to the present invention is extremely simple to assemble and install, and thus can reduce the time required for assembly, installation, and disassembly. The finishing panel fixing device also enhances fixability with respect to the finishing panel so that movement of the finishing panel due to an external force is prevented, and thus can also be applied to the finishing of an outdoor wall. The finishing panel fixing device can also facilitate maintenance.