Human cooperation robot system in which robot is caused to perform retreat operation depending on external force

A human cooperation robot system, comprising a robot configured to perform a cooperative operation with a human while sharing a workspace with each other, the system further comprising:

• an external force detecting unit that detects an external force acting on the robot;
• a retreat operation commanding unit that commands a retreat operation for causing the robot to be moved in a direction such that the external force is decreased when the external force detected by the external force detecting unit is greater than a first threshold value, if the human pushes the robot, which is in a stopped situation;
• and
• an external force variation monitoring unit that stops the retreat operation when a variation width of the external force at a predetermined time after the retreat operation is commanded by the retreat operation commanding unit is smaller than a second threshold value.