The mechanization and automation of agriculture have progressed for streamlining and saving labor of agricultural work. However there are many technical problems for automation of agriculture, because judgments based on human experiences and delicate works are sometimes required. So we propose Greenhouse Partner Robot System which is agricultural support system in greenhouse by cooperation between humans and robots. In this paper, we focused on two works, harvesting and pest control, which the introduction of simple robotics technology will be able to streamline and save labor of considerably. The system consists of Greenhouse Partner Robots and a supervisor. Greenhouse Partner Robot is a four-wheel cart which runs autonomously on a guidance line in greenhouse and has joystick based power assist function, and consists of a mobile base, a joystick, an assist bar, a sensor for tracking a guidance line and RFID tag reader. In the system, a supervisor controls Greenhouse Partner Robots without interference and Greenhouse Partner Robots operate in accordance with supervisor's commands. The experimental results using two Greenhouse Partner Robots illustrated the validity of the proposed control methods and system.