A motorized bed includes a bed body and a driving device. The bed body includes a base frame, a fixed frame, and a movable frame. The driving device includes a drive unit mounted on the fixed frame, a guide tube mounted on the drive unit, a threaded rod mounted in the guide tube, an extension tube mounted in the guide tube and having a first end provided with a push portion and a second end connected with the movable frame, and a threaded mover moved by the threaded rod and movable to abut the push portion. Thus, when a human body is disposed between the movable frame and the base frame, the human body only needs to overcome the weight of the movable frame to detach the extension tube from the mover, so that the movable frame stops moving immediately.