Abstract: A corner member for forming a foldable box has a bottom section to be attached to a corner of a bottom panel of the box and two lateral sections to be attached to portions of adjacent lateral panels of the box. The lateral sections are attached to the bottom section individually through hinge sections and are capable of being joined together by a locking mechanism when vertically raised with respect to the bottom section. An assembled box using the above corner member includes a bottom panel, lateral panels framed around the bottom panel, and the above corner member disposed at each corner portion of the box. The corner portions of the bottom panel are attached to the bottom sections of the above corner members, while two adjacent lateral panels are respectively attached to two vertically standing lateral sections of the corner member which are respectively attached to the above bottom section through hinge sections and the lateral panels are thereby framed with one another.