To provide a toilet seat lifter that reduces a burden by electrically lifting and lowering a toilet seat unit, doest not damage a driving mechanism by an overload applied during the driving of a motor in a direction of overloading making the motor lose synchronization and permits the downsizing of the driving mechanism.

The toilet seat lifer 1 lifts a moveable plate 6 to which a toilet seat unit 10 is connected by transmitting the rotational driving force of a stepping motor 7 to a right slider 51 through a speed reducing wheel train 70, an output pinion 80 and a rack 53. A control means is structured so as to make a forward driving torque to drive the stepping motor 7 in the direction of overloading making the stepping motor 7 lose synchronization smaller than the reverse driving torque to drive the stepping motor 7 in the direction opposite to the direction of overloading making the stepping motor 7 lose synchronization.