An unmanned work system comprising: a plurality of unmanned work machines that perform work while traveling without a human operator; and a management server, each of the unmanned work machines and the management server communicating with each other, wherein each of the unmanned work machines includes: an information transmission section that transmits operation information including information indicating a work state to the management server, and the management server includes: a case storage section that stores a case related to a failure in and/or a case related to maintenance of each of the unmanned work machines in association with the operation information from each unmanned work machine from which the case or cases derive; a maintenance determination section that determines, when the operation information is transmitted from the unmanned work machines, whether or not maintenance of the unmanned work machines is necessary, based on the case associated with operation information identical or similar to the operation information; and a maintenance notification section that notifies maintenance to the unmanned work machines, based on a determination result made by the maintenance determination section, wherein each of the unmanned work machines includes a blade for mowing lawn grass, characterised in that a camera that shoots a cut surface of the lawn grass mown by the blade and a mowing-target lawn area, the operation information includes information related to a load at time of lawn mowing work for mowing lawn grass and image data obtained by shooting with the camera, the operation information including the information related to the load, the case related to abrasion of the blade and/or the case related to dirt on a relevant one of the unmanned work machines are stored in the case storage section in association with each other, and the maintenance determination section identifies either the abrasion of the blade or the dirt on the relevant unmanned work machine, based on the information related to the load and the image data of the cut surface of the lawn grass and the lawn area. a plurality of unmanned work machines that perform work while traveling without a human operator; and a management server, each of the unmanned work machines and the management server communicating with each other, wherein each of the unmanned work machines includes: an information transmission section that transmits operation information including information indicating a work state to the management server, and the management server includes: an information transmission section that transmits operation information including information indicating a work state to the management server, and the management server includes: a case storage section that stores a case related to a failure in and/or a case related to maintenance of each of the unmanned work machines in association with the operation information from each unmanned work machine from which the case or cases derive; a maintenance determination section that determines, when the operation information is transmitted from the unmanned work machines, whether or not maintenance of the unmanned work machines is necessary, based on the case associated with operation information identical or similar to the operation information; and a maintenance notification section that notifies maintenance to the unmanned work machines, based on a determination result made by the maintenance determination section, wherein each of the unmanned work machines includes a blade for mowing lawn grass, characterised in that a camera that shoots a cut surface of the lawn grass mown by the blade and a mowing-target lawn area, the operation information includes information related to a load at time of lawn mowing work for mowing lawn grass and image data obtained by shooting with the camera, the operation information including the information related to the load, the case related to abrasion of the blade and/or the case related to dirt on a relevant one of the unmanned work machines are stored in the case storage section in association with each other, and the maintenance determination section identifies either the abrasion of the blade or the dirt on the relevant unmanned work machine, based on the information related to the load and the image data of the cut surface of the lawn grass and the lawn area.