A transmission apparatus for work vehicle (100A, 100B), comprising: a transmission input shaft to which rotation power is operatively input from a drive source; an HST including an HST input shaft, a pump main body supported on the HST input shaft, a motor main body hydraulically driven by the pump main body, and an HST output shaft configured to support the motor main body, the HST being configured to output traveling rotation power from the HST output shaft toward a traveling driving unit; a PTO output shaft from which rotation power is output to outside; and a PTO transmission shaft forming at least a part of a PTO transmission path from the HST input shaft to the PTO output shaft, wherein the HST input shaft is displaced from an axis of the transmission input shaft, and the HST output shaft is displaced from both axes of the transmission input shaft and the HST input shaft, the PTO transmission shaft is arranged coaxially with the transmission input shaft on a downstream side of the HST in a power transmission direction, the transmission apparatus for work vehicle (100A, 100B) further comprises an acceleration gear train configured to accelerate rotation power of the transmission input shaft, and a deceleration gear train configured to decelerate a rotation power input operatively from a second end of the HST input shaft on a downstream side in the power transmission direction, the HST input shaft operatively receives, at a first end on one side in an axial direction, the rotation power from the drive source that is accelerated by the acceleration gear train, and the PTO transmission shaft operatively receives the rotation power from a second end of the HST input shaft that is decelerated by the deceleration gear train, wherein the acceleration gear train and the deceleration gear train have such transmission ratios as that the rotation speeds of the transmission input shaft and the PTO transmission shaft are the same. a transmission input shaft to which rotation power is operatively input from a drive source; an HST including an HST input shaft, a pump main body supported on the HST input shaft, a motor main body hydraulically driven by the pump main body, and an HST output shaft configured to support the motor main body, the HST being configured to output traveling rotation power from the HST output shaft toward a traveling driving unit; a PTO output shaft from which rotation power is output to outside; and a PTO transmission shaft forming at least a part of a PTO transmission path from the HST input shaft to the PTO output shaft, wherein the HST input shaft is displaced from an axis of the transmission input shaft, and the HST output shaft is displaced from both axes of the transmission input shaft and the HST input shaft, the PTO transmission shaft is arranged coaxially with the transmission input shaft on a downstream side of the HST in a power transmission direction, the transmission apparatus for work vehicle (100A, 100B) further comprises an acceleration gear train configured to accelerate rotation power of the transmission input shaft, and a deceleration gear train configured to decelerate a rotation power input operatively from a second end of the HST input shaft on a downstream side in the power transmission direction, the HST input shaft operatively receives, at a first end on one side in an axial direction, the rotation power from the drive source that is accelerated by the acceleration gear train, and the PTO transmission shaft operatively receives the rotation power from a second end of the HST input shaft that is decelerated by the deceleration gear train, wherein the acceleration gear train and the deceleration gear train have such transmission ratios as that the rotation speeds of the transmission input shaft and the PTO transmission shaft are the same.