An opening and closing type shelf fixing clamp comprising: a main body fastened to wires forming both side edges of a shelf and to which a post is fastened; a fixing cover fastened to one side of the main body through a hinge to surround and fix a front surface of the post; and a fixing lever fastened to an opposite side of the main body through a hinge to press the fixing cover toward the main body so as to stably fix the shelf to the post wherein the fixing cover, which is fastened to the one side of the main body through the hinge to surround and fix the front side of the post, includes: a body formed therein with a post insertion portion having a semi-circular shape to fasten the post; a fastening block formed at one side of the body, inserted into an insertion portion formed at a center of the fixing block of the main body, and rotatably fastened to the main body through the hinge; a tight-contact groove formed at an opposite side of the body, and pulled toward the main body by the fixing lever after a tight-contact protrusion formed in the fixing lever is inserted into the tight-contact groove, thereby stably fixing the post; a first double locking protrusion formed at one side of the tight-contact groove, fastened to a second double locking protrusion formed on the fixing lever, and pulled toward the main body by the fixing lever to stably fix the post; and a pad fastened to the post insertion portion to prevent the shelf from descending on the post. a main body fastened to wires forming both side edges of a shelf and to which a post is fastened; a fixing cover fastened to one side of the main body through a hinge to surround and fix a front surface of the post; and a fixing lever fastened to an opposite side of the main body through a hinge to press the fixing cover toward the main body so as to stably fix the shelf to the post wherein the fixing cover, which is fastened to the one side of the main body through the hinge to surround and fix the front side of the post, includes: a body formed therein with a post insertion portion having a semi-circular shape to fasten the post; a fastening block formed at one side of the body, inserted into an insertion portion formed at a center of the fixing block of the main body, and rotatably fastened to the main body through the hinge; a tight-contact groove formed at an opposite side of the body, and pulled toward the main body by the fixing lever after a tight-contact protrusion formed in the fixing lever is inserted into the tight-contact groove, thereby stably fixing the post; a first double locking protrusion formed at one side of the tight-contact groove, fastened to a second double locking protrusion formed on the fixing lever, and pulled toward the main body by the fixing lever to stably fix the post; and a pad fastened to the post insertion portion to prevent the shelf from descending on the post. a body formed therein with a post insertion portion having a semi-circular shape to fasten the post; a fastening block formed at one side of the body, inserted into an insertion portion formed at a center of the fixing block of the main body, and rotatably fastened to the main body through the hinge; a tight-contact groove formed at an opposite side of the body, and pulled toward the main body by the fixing lever after a tight-contact protrusion formed in the fixing lever is inserted into the tight-contact groove, thereby stably fixing the post; a first double locking protrusion formed at one side of the tight-contact groove, fastened to a second double locking protrusion formed on the fixing lever, and pulled toward the main body by the fixing lever to stably fix the post; and a pad fastened to the post insertion portion to prevent the shelf from descending on the post.