A mobile robot comprising: a mobile main body; an optical pattern sensor arranged to sense obstacles around the main body; a cleaning unit arranged to suck in foreign substances around the main body during traveling; a controller arranged to extract information about the obstacles by analyzing data from the optical pattern sensor, set a traveling direction or a traveling path so as to avoid the obstacles, and thus control the main body so as to travel to a destination while avoiding the obstacles; and a travel driving unit arranged to move the main body according to control instructions from the controller, wherein the controller includes: an obstacle information acquisition unit arranged to sense the obstacles, acquire information regarding the obstacles and calculate the positions of the obstacles based on data from the optical pattern sensor; and a map generation unit arranged to generate a local area map of an environment around and within a set distance of the main body based on the information of the obstacles calculated by the obstacle information acquisition unit so that, when the mobile robot moves, the area of the local area map prior to movement and the area of the local area map after movement are different; wherein the map generation unit updates the local area map by retaining data regarding a common area (Alia) between a local area map prior to movement and a local area map after movement, adding new data according to a degree of the movement, and deleting data regarding the area from which the mobile robot has deviated. a mobile main body; an optical pattern sensor arranged to sense obstacles around the main body; a cleaning unit arranged to suck in foreign substances around the main body during traveling; a controller arranged to extract information about the obstacles by analyzing data from the optical pattern sensor, set a traveling direction or a traveling path so as to avoid the obstacles, and thus control the main body so as to travel to a destination while avoiding the obstacles; and a travel driving unit arranged to move the main body according to control instructions from the controller, wherein the controller includes: an obstacle information acquisition unit arranged to sense the obstacles, acquire information regarding the obstacles and calculate the positions of the obstacles based on data from the optical pattern sensor; and a map generation unit arranged to generate a local area map of an environment around and within a set distance of the main body based on the information of the obstacles calculated by the obstacle information acquisition unit so that, when the mobile robot moves, the area of the local area map prior to movement and the area of the local area map after movement are different; wherein the map generation unit updates the local area map by retaining data regarding a common area (Alia) between a local area map prior to movement and a local area map after movement, adding new data according to a degree of the movement, and deleting data regarding the area from which the mobile robot has deviated. an obstacle information acquisition unit arranged to sense the obstacles, acquire information regarding the obstacles and calculate the positions of the obstacles based on data from the optical pattern sensor; and a map generation unit arranged to generate a local area map of an environment around and within a set distance of the main body based on the information of the obstacles calculated by the obstacle information acquisition unit so that, when the mobile robot moves, the area of the local area map prior to movement and the area of the local area map after movement are different; wherein the map generation unit updates the local area map by retaining data regarding a common area (Alia) between a local area map prior to movement and a local area map after movement, adding new data according to a degree of the movement, and deleting data regarding the area from which the mobile robot has deviated.