In the present invention, in accordance with a tilt and back-raising command (Step S1-Yes), knee-raising operation for raising the knees of the user is performed by actuating a knee bottom placed on a top frame (Step S2). Next, after execution of the knee-raising operation, tilting operation for making the head-side height of the top frame higher than the foot-side height of the top frame by moving up and down the head side and foot side of the top frame relative to the floor (Step S3). By this, the user can take a comfortable position just like sitting in the final position after the user s back has been raised, and it is possible to reduce user s feeling of being pressed on the back and in the belly and prevent users significant body slippage.對於將利用者的背立起的最終姿勢,可以成為對於利用者接近舒服的座位的狀態,且,減少利用者的背面和腹部的壓迫感,防止利用者的身體大偏離。本發明,是對應含傾動的背提高指示(步驟S1-Yes),藉由使被載置於上部框架上的膝底作動來進行提高利用者的膝的膝提高動作(步驟S2)。接著,在膝提高動作的實行後,對於床面使上部框架的頭側及腳側昇降,進行使上部框架的頭側的高度比上部框架的腳側的高度更高的傾動動作(步驟S3)。
