A portable confinement device for confining a person upon a mattress is provided. The device includes a frame and a flexible enclosure. 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. All openings of the enclosure are designed to be unfastened only from outside of the enclosure.