In a movable bed composed by combining a bed main portion and a wheelchair, the wheelchair has chair back bottom rails having cutout portions in a chair back bottom, and a chair back guide portion installed rotatably about a rotation point with respect to a chair base portion, the chair back guide portion having sliding portions engaged with the chair back bottom rails so as to be slidable and arranged to be disengageable from the chair back bottom rails by being located in the cutout portions, and in a fourth state (flat posture), the sliding portions are located in the cutout portions, the chair back guide portion and the chair back bottom are disengaged so as to be separable from each other, and a back lifting posture of the bed main portion and the chair back bottom can be performed over the entire width of the bed, whereas in a first state (chair posture), the sliding portions are engaged with the chair back bottom rails and can slide along the chair back bottom rails.