To control body displacement when operating a back lowering movement on a gatch bed.

Bottom lowering movements are set in a controller as follows. (1) In a switch operation for a process from a back lifted condition to a back lowering movement, a knee lifting motor is switched ON, then a back lifting motor is switched to reverse ON after a time (t), the knee lifting motor is switched OFF after a prescribed time (T) has elapsed, the knee lifting motor is switched to reverse ON, a back lowering movement finishes (the back lifting motor is switched OFF) via a continuation of the back lowering movement, and (the knee lowering motor is switched OFF) after the knee lowering movement has finished, provided that T>t. Alternatively, (2) in a switch operation for a process from a gatch condition to a restoring movement (back lowering and knee lowering movements), the knee lifting motor is switched to reverse ON, the back lifting motor is switched to reverse ON, then the knee lifting motor is switched OFF after the time (t), the knee lifting motor is switched to reverse ON, the back lowering movement finishes (the back lifting motor is switched OFF) via a continuation of the back lowering movement, and (the knee lifting motor is switched OFF) after the knee lowering movement has finished.