To provide a mobile robot system capable of presenting information to a visitor appropriately, and supplying guide service according to the behavioral pattern of the visitor.

An external control device 3 is provided with a visitor detecting means 5 for detecting visitor information of the visitor 4 who entered facilities including at least one of a position, movement speed, and acceleration, a visitor's behavior presuming means 6 for presuming the behavior of the visitor 4 based on the visitor information detected by the visitor detecting means 5, a robot's behavior determining means 7 for generating a behavioral command to the mobile robot 2 based on the visitor information, and a transmitting and receiving means for transmitting the behavioral command to the mobile robot 2 by radio communication. The mobile robot 2 is provided with a robot transmitting and receiving means 10 for receiving the behavioral command from the transmitting and receiving means, and a robot control means for controlling the mobile robot 2 according to the behavioral command.