Abstract: A power controller of a linear actuator 10 in a docking device 1 including a six-axis parallel link mechanism 5, wherein a motor driver 11 configured to control rotation speed of a motor M of the linear actuator 10 on the basis of a load produced on the link 4 includes a speed controlling unit 31 that outputs a current command, a current controlling unit 32 that converts the current command to a voltage command, and a current command limiter 33 that limits the current command of the speed controlling unit 31 so that power consumption per one linear actuator 10 is one sixth or less of the power supply capacity for the motor power, thus allowing for mounting the docking device 1 even for a spacecraft with a small power supply capacity, without requiring modification of the power supply capacity.