A structure for mounting a marking plate is disclosed hereinafter as follows. A stem of a marking plate is inserted through a plate, and a spring member is provided at the tip end of the stem. Elastic portions of the spring member are elastically deformed so that a projection of each elastic portion is in elastic contact with the back surface of the plate. Accordingly, the engagement of the engaging portions of the marking plate side and the plate side and the engagement of the lock pawls and the engaging recesses are maintained by the elastic force of the elastic portions, thereby maintaining the mounted condition of the marking plate. When the marking plate is pulled away from the front surface of the plate in the mounted condition, the elastic portions are further elastically deformed to allow the disengagement.