Human-symbiotic humanoid robots that can perform tasks dexterously using their hands are needed in our homes, welfare facilities, and other places as the average age of the population increases. To improve the task performance of human-symbiotic humanoid robots, a motion-planning method with active body-environment contact was developed. Taking into account the positive and negative effect of mechanical passive elements implemented in joints, this motion-planning method can enables the hand-arm system to establish the active BE contact at the appropriate body-site and to select the joints that perform the movement for executing the given task. Control algorithms for the tool operation, namely, writing with a pen, were also constructed. The motion-planning method was validated through actual experiments on a prototype human-symbiotic humanoid robot.