Collapsible container

A collapsible container, comprising:

• a lower frame including a rectangular bottom plate having long sides and short sides;
• an upper frame that has a frame shape and a circumferential edge identical in shape to an outer rim of the lower frame and includes a pair of first lateral surfaces opposed to each other and a pair of second lateral surfaces each connecting an end of one of the pair of first lateral surfaces to an end of another of the pair of first lateral surfaces;
• lateral plates that are collapsibly supported between the lower frame and the upper frame;
• and
• a pair of lid plates that is pivotably supported to the pair of second lateral surfaces of the upper frame and thus enables opening and closing of an opening of the upper frame,
• the collapsible container being collapsible to flat form when the lateral plates are collapsed inwardly,
• wherein
• on the upper frame or the pair of lid plates, a plurality of positioning protrusions is provided to protrude upward along the circumferential edge of the upper frame,
• an installation surface provided on a lower surface of the bottom plate includes:
• a first groove that is formed along an outer circumferential edge of the bottom plate and into which the plurality of positioning protrusions of a lower one of each pair of vertically adjacent collapsible containers stacked up is fitted;
• a second groove that is formed parallel to the short sides of the bottom plate and into which a part of the plurality of positioning protrusions of a lower one of each pair of vertically adjacent collapsible containers stacked in a pinwheel configuration is fitted;
• and
• a plurality of third grooves that is formed parallel to the long sides of the bottom plate and into which support rails provided on a support surface on which the collapsible container is placed are fitted, and
• the plurality of third grooves is smaller in depth from the installation surface than the first groove and the second groove.