A control device of a work vehicle, the work vehicle including: a drive source; a traveling device driven by a driving force of the drive source; a power transmission device which has an input shaft connected to the drive source and an output shaft connected to the traveling device and transmits the driving force input to the input shaft to the output shaft; and a traction force instruction device configured to receive a traction force instruction of instructing a strength of a traction force of the traveling device, the control device comprising: a required braking force function determination unit which determines a required braking force based on a rotational speed of the output shaft and a braking force function, f characterised in that the control device comprises: a braking force function determination unit which determines at least one of an offset and an inclination for the required braking force in the braking force function, which indicates a relationship between the rotational speed of the output shaft and the required braking force and in which the required braking force monotonically increases with respect to the rotational speed, such that the stronger the traction force indicated by the traction force instruction from the traction force instruction device, the larger an absolute value of at least one of the offset and the inclination. a drive source; a traveling device driven by a driving force of the drive source; a power transmission device which has an input shaft connected to the drive source and an output shaft connected to the traveling device and transmits the driving force input to the input shaft to the output shaft; and a traction force instruction device configured to receive a traction force instruction of instructing a strength of a traction force of the traveling device, the control device comprising: a required braking force function determination unit which determines a required braking force based on a rotational speed of the output shaft and a braking force function, f characterised in that the control device comprises: a braking force function determination unit which determines at least one of an offset and an inclination for the required braking force in the braking force function, which indicates a relationship between the rotational speed of the output shaft and the required braking force and in which the required braking force monotonically increases with respect to the rotational speed, such that the stronger the traction force indicated by the traction force instruction from the traction force instruction device, the larger an absolute value of at least one of the offset and the inclination. a required braking force function determination unit which determines a required braking force based on a rotational speed of the output shaft and a braking force function, f characterised in that the control device comprises: a braking force function determination unit which determines at least one of an offset and an inclination for the required braking force in the braking force function, which indicates a relationship between the rotational speed of the output shaft and the required braking force and in which the required braking force monotonically increases with respect to the rotational speed, such that the stronger the traction force indicated by the traction force instruction from the traction force instruction device, the larger an absolute value of at least one of the offset and the inclination. a braking force function determination unit which determines at least one of an offset and an inclination for the required braking force in the braking force function, which indicates a relationship between the rotational speed of the output shaft and the required braking force and in which the required braking force monotonically increases with respect to the rotational speed, such that the stronger the traction force indicated by the traction force instruction from the traction force instruction device, the larger an absolute value of at least one of the offset and the inclination.