To appropriately notify maintenance of an unmanned work machine.In an unmanned lawn mowing system 1 including a plurality of unmanned lawn mowers 2 that perform work while traveling without a human operator and a management server 6, each of the unmanned lawn mowers 2 and the management server 6 communicating with each other, each of the unmanned lawn mowers 2 includes an information transmission section 44 that transmits operation information 52 including information indicating a work state to the management server 6, and the management server 6 includes: a case storage section 68 that stores a case related to a failure in and/or a case related to maintenance of each of the unmanned lawn mowers 2 in association with the operation information 52 from each unmanned lawn mower 2 from which the case or cases derive； a maintenance determination section 64 that determines, when the operation information 52 transmitted from each of the unmanned lawn mowers 2 is acquired, whether or not maintenance of the unmanned lawn mower 2 is necessary, based on the case associated with operation information identical or similar to the operation information 52； and a maintenance notification transmission section 66 that notifies maintenance to the unmanned lawn mowers 2, based on a determination result made by the maintenance determination section 64.
