A map data memory stores map data of a movement region, position data of a marker at a predetermined place in the movement region, identification data of the marker, and position data of a boundary line near the marker in the movement region. A marker detection unit detects the marker in an image, based on the position data of the marker and the identification data. A boundary line detection unit detects the boundary line near the marker from the image. A parameter calculation unit calculates a parameter of the boundary line in the image. A position posture calculation unit calculates a position and a posture of the mobile robot in the movement region, based on the parameter and the position data of the boundary line.