A mobile robot system includes an outside world sensor, a traveling unit, and a control unit. The control unit is configured to provide a history map data. Based on environment information obtained from the outside world sensor, a mobile object appearance point at which no mobile body exists at present but there is the possibility that a mobile body may appear in the future is recognized. In recognizing a door as the mobile object appearance location, if part of an object being obtained from the outside world sensor and having a width equal to or greater than a predetermined width set in advance belongs to an object movement position recorded in the velocity history map, then the part is recognized as a door.