A turbomachine includes: a rotational shaft; a pair of thrust collars disposed around the rotational shaft; a thrust bearing disposed around the rotational shaft at an axial directional position between the pair of thrust collars; and an oil-drain channel disposed around the rotational shaft, for draining lubricant oil after lubricating a sliding portion between the thrust bearing and the thrust collars. The oil-drain channel includes: an oil-drain port portion for discharging the lubricant oil inside the oil-drain channel downward; and an oil-guide channel portion disposed above the oil-drain port portion and configured to guide the lubricant oil from the sliding portion in a circumferential direction of the rotational shaft to the oil-drain port portion. The oil-guide channel portion has an asymmetric shape with respect to a rotational direction of the rotational shaft, the oil-guide channel portion having a minimum flow-path cross sectional area at a first position on an upstream side in the rotational direction, and a maximum flow-path cross sectional area at a second position on a downstream side of the first position.