A storage container of a storage container for a refrigerator, which is configured to mount the storage container for storing articles therein to a storage container seating portion formed in a rear surface of a refrigerator door by using a mounting protrusion and locking mechanism provided on the storage container and a mounting groove and catching protrusion provided on the storage container seating portion. The mounting structure includes a storage container seating portion depressed into a portion of a rear surface of a door; a storage container seated in the storage container seating portion and formed with a space for storing articles therein; a mounting protrusion and mounting groove formed on the storage container seating portion and storage container, respectively, at positions corresponding to each other to be matched in shape with each other and used for fixing the storage container into the storage container seating portion; and a locking mechanism provided on a portion of the storage container for locking the storage container into the storage container seating portion by causing a portion of the locking mechanism to be caught to a protruding portion of the storage container seating portion.