<p>A vertical power unit includes an input shaft and an output shaft (20) which have axes in the vertical direction and are vertically arranged to each other; and a torque converter between the input shaft and the output shaft (20). The output shaft (20) includes an upper output shaft connected to a turbine runner (26) and a lower output shaft connected to the upper output shaft. An oil tank (22) and an oil pump (41) are provided outside the torque converter. The upper output shaft is provided with a vertical hole which communicates at an upper end with a circulation circuit (28) of the torque converter so as to introduce the oil (23) discharged by the oil pump (41) into the circulation circuit (28), and a bottom wall which closes a lower end of the vertical hole. Thus, an working oil (23) is constantly supplied to the circulation circuit (28) of the torque converter through the interior of the output shaft (20), thereby cooling the working oil (23) in the circulation circuit (28), and improves maintainability of loading devices driven by the output shaft (20).</p>
