Oil-drain device for thrust bearing device and turbocharger provided with the same

An oil-drain device for a thrust bearing includes: a rotor shaft; a collar member mounted to an outer periphery of the rotor shaft; a thrust bearing supporting the rotor shaft in an axial direction; and an oil-drain space forming member defining an oil-drain space through which lubricant oil leaking from a sliding portion of the thrust bearing flows, between the thrust bearing and the oil-drain space forming member. The oil-drain space includes: an oil-drain channel defined between a first end surface of the thrust bearing and a first end surface of the oil-drain space forming member, surrounding the flange portion of the collar member; and an oil-drain port formed below the oil-drain channel, for discharging the lubricant oil flowing through the oil-drain channel outside the oil-drain space. The oil-drain space is configured to guide the lubricant oil flowing through the oil-drain channel to outside the oil-drain space via the oil-drain port, along a flow direction of the lubricant oil flowing through the oil-drain channel from an upstream side toward a downstream side in a rotational direction of the rotor shaft.