A work-vehicle position measurement device includes a ground reference station (19) configured to receive a radio wave from a satellite, measure an own position, and transmit a result of the measurement to outside, and a work vehicle including a position calculation unit (16) configured to execute position calculation of obtaining an own vehicle position in accordance with received information via the radio wave from the satellite and transmitted information from the reference station (19), a travel control unit (17) configured to control a travel state of a vehicle body so that the vehicle body travels along a set route in accordance with a result of the calculation by the position calculation unit (16), and a position information management unit (100) configured to manage map data of a work target field and position data of the reference station (19) for the field in association with each other.