A robot system comprising a robot and a controller configured to control motion of the robot, the controller comprising: a motion mode storage unit storing a plurality of motion modes for controlling the robot to switch a motion state of the robot from a normal motion state to a special motion state when a predetermined first condition is satisfied; and a motion mode switching unit configured to switch the motion mode of the robot to another motion mode when, while a particular motion mode stored in the motion mode storage unit is in execution, a predetermined second condition for the particular motion mode is satisfied with a first condition for the particular motion mode satisfied; the robot system further comprising a moving body detector that detects a position of a moving body other than the robot, wherein: the motion mode storage unit stores a first motion mode; the first condition of the first motion mode is that the moving body is detected within a predetermined area around the robot, the special motion state of the first motion mode is a state in which the robot is stopped, the robot system being characterized by: the second condition of the first motion mode is that the state in which the moving body is detected within the predetermined area around the robot has continued for a predetermined period or more; the motion mode switching unit is configured to switch the motion mode of the robot from the first motion mode to a fourth motion mode when the second condition is satisfied during the execution of the first motion mode; the first condition of the fourth motion mode is that the moving body is detected within the predetermined area around the robot; and the special motion state of the fourth motion mode is a special motion mode in which the operation is made at lower power than normal. a motion mode storage unit storing a plurality of motion modes for controlling the robot to switch a motion state of the robot from a normal motion state to a special motion state when a predetermined first condition is satisfied; and a motion mode switching unit configured to switch the motion mode of the robot to another motion mode when, while a particular motion mode stored in the motion mode storage unit is in execution, a predetermined second condition for the particular motion mode is satisfied with a first condition for the particular motion mode satisfied; the robot system further comprising a moving body detector that detects a position of a moving body other than the robot, wherein: the motion mode storage unit stores a first motion mode; the first condition of the first motion mode is that the moving body is detected within a predetermined area around the robot, the special motion state of the first motion mode is a state in which the robot is stopped, the robot system being characterized by: the second condition of the first motion mode is that the state in which the moving body is detected within the predetermined area around the robot has continued for a predetermined period or more; the motion mode switching unit is configured to switch the motion mode of the robot from the first motion mode to a fourth motion mode when the second condition is satisfied during the execution of the first motion mode; the first condition of the fourth motion mode is that the moving body is detected within the predetermined area around the robot; and the special motion state of the fourth motion mode is a special motion mode in which the operation is made at lower power than normal. the motion mode storage unit stores a first motion mode; the first condition of the first motion mode is that the moving body is detected within a predetermined area around the robot, the special motion state of the first motion mode is a state in which the robot is stopped, the robot system being characterized by: the second condition of the first motion mode is that the state in which the moving body is detected within the predetermined area around the robot has continued for a predetermined period or more; the motion mode switching unit is configured to switch the motion mode of the robot from the first motion mode to a fourth motion mode when the second condition is satisfied during the execution of the first motion mode; the first condition of the fourth motion mode is that the moving body is detected within the predetermined area around the robot; and the special motion state of the fourth motion mode is a special motion mode in which the operation is made at lower power than normal. the second condition of the first motion mode is that the state in which the moving body is detected within the predetermined area around the robot has continued for a predetermined period or more; the motion mode switching unit is configured to switch the motion mode of the robot from the first motion mode to a fourth motion mode when the second condition is satisfied during the execution of the first motion mode; the first condition of the fourth motion mode is that the moving body is detected within the predetermined area around the robot; and the special motion state of the fourth motion mode is a special motion mode in which the operation is made at lower power than normal.