A rotary machine comprises a hub including: a blade-facing hub portion including a first blade-facing surface which faces a spherical hub-side end surface of a variable blade and which has a first spherical region having a spherical shape; an upstream hub portion disposed upstream of the blade-facing hub portion in an axial direction of the hub and having a first outer-peripheral surface being adjacent to the first blade-facing surface in the axial direction; and a downstream hub portion disposed downstream of the blade-facing hub portion in the axial direction and having a second outer peripheral surface being adjacent to the first blade-facing surface in the axial direction. At least one of following condition (a) or (b) is satisfied: (a) a downstream end of the first outer peripheral surface is disposed on an outer side of an upstream end of the first blade-facing surface in the radial direction of the hub; (b) an upstream end of the second outer peripheral surface is disposed on an outer side of a downstream end of the first blade-facing surface in the radial direction of the hub.