A portable confinement device for confining a person upon a mattress is provided. The device includes a frame and a flexible enclosure. The frame includes a base member and at least two upright members. The upright members include support portions and bridge portions connecting the support portions. The bridge portions are connected to the support portions by lockable hinges. When the hinges are locked, the bridge portions are in an upright position. When the hinges are unlocked, the bridge portions are in a downward, lowered position. The enclosure is supported by and sits upon the frame to stabilize the device from tipping over. A mattress may be received into the interior space of the enclosure. The enclosure includes an opening for allowing a person to enter or exit the interior space of the enclosure.