PURPOSE: To attain the safe and speedy escape of a patient and to travel a mobile bed in an abnormal place by providing a mattress, which is deformed in a box shape, and an infinite track.

CONSTITUTION: An elastic body 1 to have extension force in an external side is compressed and built in a mattress 2 and at a normal time, the mattress is pressed by a claw 4 which is supported by a length-wise frame 3. At the time of the escape, when the claw 4 is detached, the mattress 2 is deformed in the box shape and the patient is safely protected and sandwiched by the bed length-wise frame 3 by reducing a breadth-wise frame 5 of a double cylinder. Then, the reduction of a bed area causes the speedy escape to be easy at the time of confusion. When the abnormal place is steps or a channel, etc., a free caster 6 is separated from a grounding surface 7 and an infinite track 8 falls down and is grounded. Then, the mobile bed is traveled.