1. A management system of a mining machine comprising: a detecting unit mounted on the mining machine which travels in an unmanned state in a mine in which a plurality of landmarks is located, the detecting unit detecting a position of a landmark relative to the mining machine in a contactless manner; a travel control unit which corrects a current position of the mining machine based on a position of the landmark obtained in advance and the position of the landmark obtained by the detecting unit and allows the mining machine to travel by dead reckoning navigation; a travel limiting unit which stops the mining machine when the mining machine travels a first distance after starting traveling by the dead reckoning navigation; and a travel limitation relaxing unit which extends the first distance when the position of the landmark obtained in advance is present within a range of a second distance in a travel direction of the mining machine from a position, as a reference, where the mining machine reaches when the mining machine travels the first distance after the mining machine starts traveling by the dead reckoning navigation.