In (α, β) coordinates defined by a back angle α and a knee angle β, a pattern that connects between a coordinate point (0, 0) at which each of a back bottom and a knee bottom is horizontal and a coordinate point (α0, β0) which is a final reaching point for a back lift-up operation and at which the back bottom is lifted up by a plurality of points is set, an optimal pattern which provides less slipperiness and less oppressive feeling is acquired beforehand, and a control section moves the back bottom and the knee bottom along the optimal pattern. This reliably prevents a carereceiver from slipping, regardless of subjective judgment by an operator or a carer, at the time of performing a back lift-up operation and back lift-down operation of an electric bed. It is therefore possible to prevent pressure from being applied onto the abdominal region and chest region of the carereceiver, thus relieving the carereceiver and carer of the burden.