A mobile robot, comprising: a drive unit configured to move a main body; an input unit provided with a camera configured to receive image information; an output unit; a communication unit configured to communicate with position information transmitters (50, 50M, 51, 52, 53, 54, 55) installed within an area, wherein the position information transmitters (50, 50M, 51, 52, 53, 54, 55) are configured to transmit signals to the mobile robot; and a controller configured to calculate location determination-related data based on at least one of a first signal transmitted between the position information transmitters (50, 50M, 51, 52, 53, 54, 55) and a second signal transmitted between the main body and the position information transmitters (50, 50M, 51, 52, 53, 54, 55) within the area, wherein the controller is configured to sense the entry of a moving object into the area and to perform an operation corresponding to the sensing of the entry based on whether an amount of change in the calculated location determination-related data is out of a reference range, characterized in that the location determination-related data comprises at least one of distance information, signal strength information, and signal direction and angle information, which are calculated based on the first signal and a response signal to the first signal and/or based on the second signal and a response signal to the second signal, wherein the controller is configured to output a preset warning alarm through the output unit with an operation corresponding to the sensing of the entry and to control the drive unit to rotate or move the main body toward the sensed position of the moving object with an operation corresponding to the sensing of the entry such that the sensed position of the moving object is within a field of view of the camera, wherein the mobile robot is configured to perform a photographing operation to acquire image information on the moving object, and wherein the image information is sent to one or more of a preset external terminal, an external server, and a security company when a preset condition is satisfied. a drive unit configured to move a main body; an input unit provided with a camera configured to receive image information; an output unit; a communication unit configured to communicate with position information transmitters (50, 50M, 51, 52, 53, 54, 55) installed within an area, wherein the position information transmitters (50, 50M, 51, 52, 53, 54, 55) are configured to transmit signals to the mobile robot; and a controller configured to calculate location determination-related data based on at least one of a first signal transmitted between the position information transmitters (50, 50M, 51, 52, 53, 54, 55) and a second signal transmitted between the main body and the position information transmitters (50, 50M, 51, 52, 53, 54, 55) within the area, wherein the controller is configured to sense the entry of a moving object into the area and to perform an operation corresponding to the sensing of the entry based on whether an amount of change in the calculated location determination-related data is out of a reference range, characterized in that the location determination-related data comprises at least one of distance information, signal strength information, and signal direction and angle information, which are calculated based on the first signal and a response signal to the first signal and/or based on the second signal and a response signal to the second signal, wherein the controller is configured to output a preset warning alarm through the output unit with an operation corresponding to the sensing of the entry and to control the drive unit to rotate or move the main body toward the sensed position of the moving object with an operation corresponding to the sensing of the entry such that the sensed position of the moving object is within a field of view of the camera, wherein the mobile robot is configured to perform a photographing operation to acquire image information on the moving object, and wherein the image information is sent to one or more of a preset external terminal, an external server, and a security company when a preset condition is satisfied.