The invention provides a hydraulic machine and a method of operating the same. The hydraulic machine can restrain hydraulic pressure fluctuation caused by a rotation mode and a stretching mode of whirlpool generated on a downstream side of a runner. In one embodiment, a hydraulic machine includes a runner including a plurality of blades arranged in a ring shape, a crown connected to the blades from an upper side and having a lower end surface at a position surrounded by the blades, and a band connected to the blades from a lower side, the runner being configured to convert energy of pressured water into rotational energy. The machine further includes a main shaft configured to transmit the rotational energy of the runner to a generator, and a draft pipe located downstream of the runner, and configured so that the water used to drive the runner flows into the draft pipe. The machine further includes a columnar member disposed on a rotation axis of the main shaft below the crown, and having a diameter smaller than a diameter of the lower end surface of the crown.