A memory card casing includes a plastic framework, and upper and lower metal covers that could be conveniently assembled to two sides of the plastic framework. The metal covers are fastened to each other via fastening means spaced on perpendicular wall portions of the metal covers. Each of the fastening means includes first and second fastening plates. The plastic framework is provided with retaining means, each of which includes a neck portion inward projected from and perpendicular to inner wall surface of the plastic framework and an expanded head portion in front of the neck portion. When the two metal covers are closed onto two sides of the plastic framework, the second fastening plates are located in recesses defined by the first fastening plates with tongues provided on the first fastening plates extended through retaining holes defined by the second fastening plates to firmly hold the two fastening plates together, and the neck portions are confined in holes defined by spaces on the wall portions of the metal covers between any two adjacent fastening plates to prevent the expanded head portions and, accordingly, the whole plastic framework from separating from the closed metal covers.