A modular adjustable bed includes a bed frame unit, front and rear sliding frames disposed to be slidable on the bed frame unit, a head support frame pivotally mounted on the front sliding frame, a pair of prop links coupling the head support frame to a front frame of the bad frame unit, and a leg support frame pivotally mounted on the rear sliding frame. When the head support frame is driven to be displaced to a head elevated position from a head normal position, the front sliding frame is displaced to a front position from a rear position. The leg support frame can be driven to move from a leg normal position to a leg elevated position.
