Seat lifter

A seat lifter comprising:

• an inner link for changing a height position of an inner lower arm with respect to a floor of a vehicle, the inner lower arm being disposed on an inner side in a width direction of the vehicle;
• an outer link for changing a height position of an outer lower arm with respect to the floor, the outer lower arm being disposed outside the inner lower arm in the width direction;
• a coupling rod that couples the inner link to the outer link so as to cause the inner link and the outer link to rotate together;
• a planetary gear mechanism connected to the coupling rod and capable of causing the coupling rod to rotate relative to the inner lower arm and the outer lower arm;
• a drive unit capable of driving the planetary gear mechanism;
• and
• a power transmission rod that transmits power of the drive unit to the planetary gear mechanism,
• the planetary gear mechanism being disposed between the inner lower arm and the outer lower arm, and
• the drive unit being disposed outside the inner lower arm in the width direction or outside the outer lower arm in the width direction.