To provide a landmark device that allows position control with high precision over a wide range and that is structurally very simple.

The landmark device includes a short-range landmark set 400 having two marks Mn spaced a predetermined distance apart, and a long-range landmark set 500 having two marks Mf spaced a wider distance apart than the short-range landmark set 400. When a mobile robot 200 is located away from the landmark device 300, the marks Mf of the long-range landmark set 500 where two points are at a distance from each other are used to perform position recognition for the distance between the landmark device 300 and the mobile robot 200, their directions and the like. As the moving robot 200 approaches the landmark device 300, position recognition is performed using the marks Mn of the short-range landmark set 400.

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